added observer method to more easily encapsulates KVO
added tests for invalid method signatures and fixed bug where it incorrectly passed
added checks for matching return type and the appropriate tests
renamed to TWTKeyValueObserver
added custom inits to header and blocked the use of init by throwing a not recognized selector
added options parameter to allow the developer to specify the required options
refactored away method signature match method for the simpler target:hasValidSignatureForSelector:
slighly refactored compare signature method and added tests for NSMethodSignature category
clean up formatting for consistency
renamed changingObject to observedObject to be more consistent with apple's terminology
added podspec with subspecs for categories and kvo
updated readme with information about new subspecs
added readonly versions of the properties to the header and removed unused property
renamed categories to be more specific Method Signature Equality
updated readme to include updated subspec
Merge pull request #30 from twotoasters/kvo-additions

Added KVO Observer Object