amended rails upgrade plugin instructions to be rails 2.3.x compatible instead of former rails 3 format

adding documentation regarding time_zone_aware_attributes and skip_time_zone_conversion_for_attributes

I am working on removing all traces of superclass_delegating_accessor from rails code base.

https://rails.lighthouseapp.com/projects/8994/tickets/2914-superclass_delegating_accessor-needs-to-be-deprecated-nicely

adding comment specifying that cattr_accessor also supports instance_write and instance_rader option

Revert "Frameworks are loaded in application.rb rather than config.rb according to Rails 3 conventions."

This reverts commit 1793b214.

This commit had no risk, but docrails has a hard rule about touching code.
The contribution is appreciated, I hope you do not mind this technical
revert. I'll apply that to master with proper credit.

amended Contributing to Rails guide to advise to use bundler v1.0 to avoid error messages with bundler

Signed-off-by: NWincent Colaiuta <win@wincent.com>

This resolves issues for libraries which use '_' prefixed keys in their
attributes hash, such as Mongoid. A key like "_id" or "_type" will no
longer be converted to "<-id>" and "<-type>".
Signed-off-by: Nwycats <wycats@gmail.com>