README draft

@mgorbach 

Draft of the README.

**NOTE: This is a pull request to merge into #8. If that PR is merged first, this will need to be reopened into `development`**.

#### Related Issues
Potentially closes #2.

#### TODO
- Add link to CocoaDocs page when podspec is submitted

There won't be a URL for the CocoaDocs until I submit the podspec and the docs are generated. I can add it as a separate task, I was planning on taking care of it before the develop branch is merged to master.