Merge pull request #4 from rousisk/patch-1

Provide some installation instructions in readme

README.rdoc

@@ -6,6 +6,16 @@ Never again will you accidentally delete production data!  Rack::Environmental a
 an indicator badge to your web application so that you can tell whether you're
 working with the staging, test, development or production version of your web app.
 
+== Installation
+
+For bundler-managed applications just include Rack::Environmental in your Gemfile:
+
+    gem 'rack-environmental'
+
+Alternatively, you can install Rack::Environmental manually:
+
+    $ gem install rack-environmental
+
 == Usage
 
 This Rack middleware can be used with any Rack application, but here's how you would
@@ -48,4 +58,4 @@ Here's the full list of configuration options:
 If there's a context where you want Rack::Environmental to specifically ignore your
 requests, such as a Jasmine test runner which returns essentially empty files to be
 built on by the test runner, you can "shut off" Rack::Environmental for that context
-by adding `:style => :none` to its options.
+by adding `:style => :none` to its options.