Merge pull request #80 from akitchen/UpdatedREADME

Some updates to the README
Re-enable testing against older iOS SDKs in CI

The more SDKs we work against the merrier! Looks like Travis has re-added
support for testing against the 5.0 and 5.1 iOS SDKs since we had to originally
take them out in this commit:

    8aef6e7ccfbce87b6cf170260ce08e1faf3d7f83
Merge pull request #81 from xoebus/ci-old-sdks

Re-enable testing against older iOS SDKs in CI
Fix target membership of CDRDefaultReporterSpec
Merge pull request #82 from mountainstyle/master

Fix target membership of CDRDefaultReporterSpec
A failing spec for more specific handling of optional protocol methods
Implements more specific handling of optional protocol methods.

- nice fakes respond to optional protocol method selectors
- strict fakes require optional methods to be stubbed or they don't
  respond to their selector