CSlim Objective-C Changes

Several updates since the previous Pull Request.

- Cleaned up the code
- Added Specs for the changes.
- Added support for Query Tables with conversion between NSArray and SlimLists
- Fixes a bug relating to symbol replacement when used in the same test page as a table.
- Simpler Podspec for CocoaPods support
- Bumped supported string to 0.3 of Slim to work with recent releases of Fitnesse.