Exteneded features to support RZVinyl

@Raizlabs/maintainers-ios 
These are some extended features to support RZVinyl, since it needs to make use of some of the internals. I tried to keep the private stuff clearly marked as such, and the podspec specifies exclusion of the private headers as well.

#### TODO:

- [x] #6 Document README with cocoapods installation instructions.
- [x] #7 Prepare podpec for release

**Note:** This is intended to be a living pull request until this is vetted and all the TODOs above are addressed.