Add public accessors for types... (XCode 6b4)

This is the first step in getting Nimble ready for XCode 6 beta 4.

The following things are included in this:
- public accessors added
- removed the bridging header (not supported in Frameworks)
- forward declared NMBExpectation (was getting an error related to it)

I'm still getting an error related to:

Undefined symbols for architecture x86_64:
  "_OBJC_CLASS_$_NMBExpectation", referenced from:
      objc-class-ref in DSL-B83371164C24FC7F.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)

But I'm unfamiliar with what the problem is here.
Correct range usage.

Per @blindsey's notes, prior change was negating a conditional/nil.
Correct NMBExpectation to be public.

Per @sync's notes on pull request 8.
Add more public accessors to get tests compiling.

Remaining items:
- Matcher and BasicMatcher not conforming errors
- Invalid redeclaration of 'to' (compiler seems to have trouble
  differentiating between Matcher and BasicMatcher again)
Corrected mistype with negating range
Framework is compiling now, one test isn't yet.

Some notes about the changes here:

* made Matcher inherit from BasicMatcher - this way methods that take a Matcher instance can also take a BasicMatcher
* failsWithErrorMessage is crashing the running of the tests right  now... not sure why yet
* Expectation methods that do the actual matching are internal and named toImpl and toNotImpl respectively. I was getting "invalid redeclaration" errors between these methods and the extension methods.
* They're internal so that all public access can go through the extension methods.
* testArrayEquality is failing to compile right now, specifically calls that take an Array<Int> in as opposed to an array literal (like [1,2,3]). Not sure about that yet.
Fix for beta 4 compatibility
Converted all references to line numbers to UInt
Tweaks to README source code and description
Refactored ObjCMatcher and test.sh file