refactor RemoteIp middleware

Unneeded require 'active_support/memoizable'

- return the last forwarded IP before REMOTE_ADDR to handle proxies
- remove completely superfluous RemoteIpGetter class
- remove duplication of trusted proxies regexp
- remove unused constant from Request
- move comments from Request to where they are actually relevant
- edit comments for clarity of purpose

The original code (confusingly) tried to return REMOTE_ADDR both at the beginning and the end of the chain of options. Since REMOTE_ADDR is _always_ set, this is kind of silly. This change leaves REMOTE_ADDR as the last option, so that proxied requests will be assigned the correct remote IP address.

Fix wording and minor typos in the Responder RDoc

AS::Callbacks::Callback#_compile_option refactored

Prevent multiple SHOW TABLES calls when a table don't exists in database...

AS::Callbacks.__run_keyed_callback: remove unused cache

Modify change_table to remove the need for the block argument

Checking the arity of the block passed to create_table

A recent change made to create_table does away with the
need for the block argument. Checking the arity will prevent the
mixing up of the two syntaxes.

in the template name while generating guide related pages
like index, layout and credits

Fix and simplify highlight regexp

Fixed error with 'rails generate new plugin' where the .gitignore was not

AS::Callbacks._define_runner better abstraction

AC::Metal#response_body= stores different value in Ruby 1.8 and 1.9

Incapsulate the logic of keyed callback method definition and execution
in the separated method.

Fixed error with 'rails generate new plugin' where the .gitignore was not properly generated if --dummy-path was used and added test case

A test case to ensure that AC::Metal#response_body= always wraps the given value in an Array in both Ruby 1.8 and 1.9 (refs #3581)

Extend IRB right before starting IRB to remove dependency on IRB from Rails::Application

move Rails console top level methods to IRB context

Modulize Rails console methods so that other console libraries such as Pry can include these methods

CHANGELOG => CHANGELOG.md

I missed these in previous commit

Refactor test:uncommitted task.

Thanks to @sobrinho (Gabriel Sobrinho)