Add reset cli flag (refs eslint#692)

Adds a --reset flag to the cli options that resets all
default rules to be off.

docs/command-line-interface/README.md

@@ -26,6 +26,7 @@ Options:
   -c, --config path::String  load configuration data from this file
   --rulesdir path::String    load additional rules from this directory
   -f, --format String        use a specific output format - default: stylish
+  --reset                    set all default rules to off
   -v, --version              outputs the version number
 ```
 
@@ -65,7 +66,15 @@ Example:
 
     eslint --rulesdir my-rules/ file.js
 
-The rules in your custom rules directory must following the same format as bundled rules to work properly.
+The rules in your custom rules directory must follow the same format as bundled rules to work properly.
+
+### `--reset`
+
+This option turns off all rules enabled in ESLint's default configuration file located at `conf/eslint.json`. ESLint will still report syntax errors.
+
+Example:
+
+    eslint --reset file.js
 
 ### `-v`, `--version`
 

lib/config.js

@@ -125,7 +125,8 @@ function Config(options) {
 
     this.cache = {};
     this.exclusionsCache = {};
-    this.baseConfig = require(path.resolve(__dirname, "..", "conf", "eslint.json"));
+    this.baseConfig = options.reset ? {} :
+            require(path.resolve(__dirname, "..", "conf", "eslint.json"));
     this.baseConfig.format = options.format;
     useConfig = options.config;
 

lib/options.js

@@ -44,5 +44,9 @@ module.exports = optionator({
     alias: "v",
     type: "Boolean",
     description: "Outputs the version number."
+  }, {
+    option: "reset",
+    type: "Boolean",
+    description: "Set all default rules to off."
   }]
 });

tests/lib/cli.js

@@ -226,4 +226,13 @@ describe("cli", function() {
             assert.equal(exit, 1);
         });
     });
+
+    describe("when executing with reset flag", function() {
+        it("should execute without any errors", function () {
+            var exit = cli.execute("--reset tests/fixtures/missing-semicolon.js");
+
+            assert.isTrue(console.log.notCalled);
+            assert.equal(exit, 0);
+        });
+    });
 });