Add CONTRIBUTING.md

Added a file to describe general guidelines for submitting pull requests.

CONTRIBUTING.md

@@ -0,0 +1,179 @@
+# Bug reports / Github pull-requests
+
+When reporting a bug or submitting a pull request, make sure you search
+[JIRA](http://jira.qos.ch/browse/LOGBACK) and
+[GitHub pull requests](https://github.com/qos-ch/logback/pulls)
+for the same/similar issues. If you find one, feel free to add a `+1` comment
+with any additional information that may help us solve the issue.
+
+When creating a new bug report, be sure to state the following:
+
+* Detailed steps to reproduce the bug
+* The version of logback and SLF4J you are using
+* Operating system and its version, any other relevant environment details
+
+
+# Submitting a pull-request
+
+## Before you begin
+Is this the right place for the PR?
+
+YES:
+ * If it's a **bug fix** for logback proper (`logback-core`,
+   `logback-classic`, `logback-access`)
+ * If it's a **new feature** (such as an appender), and you're willing to
+   submit a [signed CLA](http://logback.qos.ch/cla.txt)
+
+NO:
+ * If it's a **new feature**, but you prefer not to submit a signed CLA
+ * If it's a **new feature**, and you wish to see it released sooner than
+   logback's release schedule
+
+If your PR falls into the *NO* category, please submit it to either
+[`logback-extensions`](https://github.com/qos-ch/logback-extensions)
+(no CLA required, shorter release cycles than logback, Apache License)
+or [`logback-contrib`](https://github.com/qos-ch/logback-contrib)
+(CLA required, shorter release cycles than logback, same license as logback).
+
+## Instructions
+ 1. [Fork](https://help.github.com/articles/fork-a-repo) the repo on GitHub.
+ 2. Make a [topic branch](https://github.com/dchelimsky/rspec/wiki/Topic-Branches#using-topic-branches-when-contributing-patches)
+    and start hacking.
+ 3. If your branch becomes several commits behind master, be sure to rebase
+    to avoid a merge conflict.
+ 3. Submit a pull-request based off your topic branch, following the patch
+    rules below.
+ 4. If your patch is non-trivial and you haven't submitted a [signed CLA](http://logback.qos.ch/cla.txt),
+    please email it to ceki@qos.ch and tony19@gmail.com with **\[logback]
+    signed CLA** in the subject line. Trivial bug fixes (less than ~30 lines)
+    do not require a CLA.
+
+## Patch rules
+
+ **P1.** The patch MUST follow the [general logback code style](General style notes).
+     Disable your IDE's auto-formatting for logback files (unless you're using
+     the logback [`codeStyle.xml`](https://github.com/qos-ch/logback/blob/master/codeStyle.xml)
+     file in Eclipse).
+
+ **P2.** Small focused patches are preferred. The patch MUST NOT mix new features
+     and bug fixes in the same pull-request. Also exclude reformatting from
+     the pull-request (move that to its own commit or another pull-request).
+
+ **P3.** Large changes to the code SHOULD be discussed with the core team first.
+     Create an issue, explaining your plan, and see what we say.
+
+ **P4.** The commit message SHOULD be formatted as described in http://tbaggery.com/2008/04/19/a-note-about-git-commit-messages.html
+     and indicate the appropriate JIRA key.
+
+ **P5.** Pull-requests MUST NOT contain intermediate commits (e.g., bug fixes to
+     your own patch, refactoring your own patch), which should be [squashed and
+     then force-pushed to your branch](https://github.com/edx/edx-platform/wiki/How-to-Rebase-a-Pull-Request).
+     Fewer commits are better.
+
+ **P6.** Unit tests MUST be included for behavioral changes or new features.
+
+ **P7.** Pull-requests MUST include an update in the release notes that clearly
+     describe your changes and the appropriate JIRA key. This will likely
+     mimic your commit message.
+
+ **P8.** Pull-requests MUST include updates to logback's documentation pages,
+     where necessary. Examples where this would be required:
+        * adding/removing a configuration flag to `SyslogAppender`
+        * adding a new appender to `logback-classic`
+
+# General style notes
+
+Please note that most of the formatting rules are provided in
+[codeStyle.xml](https://github.com/qos-ch/logback/blob/master/codeStyle.xml)
+in the root directory of logback.
+
+> **When in Rome, code like the Romans do**.
+
+ **S1.** Use 2-space indents.
+
+ ```java
+// bad
+class Foo {
+   public static void main(String[] args) {
+       System.out.println("hello world!");
+   }
+}
+
+// good
+class Foo {
+ public static void main(String[] args) {
+   System.out.println("hello world!");
+ }
+}
+ ```
+
+ **S2.** Closing-curly bracket should be on its own line. Opening-curly bracket
+     should not.
+
+ ```java
+// bad
+if (foo)
+{
+  ...
+}
+
+// bad
+if (foo)
+{ ... }
+
+// bad
+if (foo) {
+  ... }
+
+// good
+if (foo) {
+  ...
+}
+ ```
+
+ **S3.** Delimit keywords and brackets with a space.
+
+ ```java
+// bad
+try{
+  ...
+}catch(Exception e){
+  ...
+}
+
+// good
+try {
+  ...
+} catch (Exception e) {
+  ...
+}
+ ```
+
+ **S4.** Add logback's standard file-header to any new files.
+
+ ```java
+/**
+ * Logback: the reliable, generic, fast and flexible logging framework.
+ * Copyright (C) <year>, QOS.ch. All rights reserved.
+ *
+ * This program and the accompanying materials are dual-licensed under
+ * either the terms of the Eclipse Public License v1.0 as published by
+ * the Eclipse Foundation
+ *
+ *   or (per the licensee's choosing)
+ *
+ * under the terms of the GNU Lesser General Public License version 2.1
+ * as published by the Free Software Foundation.
+ */
+  ```
+
+ **S5.** Add javadoc for public functions (we won't fault you for skipping private
+     functions unless comments are warranted).
+
+ **S6.** Code for maintainability. We would rather a function be a couple of lines
+     longer and have (for example) some [explaining variables](http://www.refactoring.com/catalog/extractVariable.html)
+     to aid readability.
+
+ **S7.** If you find that a file has two different styles in use, defer to the
+     standard style notes here. You can submit a PR to only fix the formatting.
+