Removing usage of UITextAlignment when building against iOS 7 SDK

Remove duplicated blocks when using NSLineBreakMode and define NIIOS_7_0.
Merge pull request #413 from liquidx/master

Update compile time checks to avoid usage of UITextAlignment under iOS 7 SDK and remove duplicated NSLineBreakMode conversion code.
Adds new methods that allow setting a custom accessoryView directly when mapping objects/classes with tableview cell actions
- Removes attachToClass methods.
- Handles nil accessoryView
Merge pull request #416 from chriscox/table-accessoryView

Add support for attaching custom accessoryViews to table model objects.
Fix missing UIKit import in NIActions after accessory view support addition.
Fix problematic override of accessoryView in willDisplayCell that overwrites other places that set the accessoryView.
Revert changes to add an accessoryView action.
Merge pull request #417 from liquidx/master

Revert adding support for accessoryView declaration to NIActions and NITableViewActions.
Merge branch 'master' of https://github.com/jverkoey/nimbus