Fixed unit tests for Android and iOS linters

Summary:
Unit tests for Android linter mysteriously started working. All I did was uncomment it.
Changed oclint.sh to point to iOS 7.0 SDK. Updated readme to match.

Test Plan: Run `arc lint`.

Reviewers: mbishop

Reviewed By: mbishop

CC: ablackwood

Differential Revision: https://devportal.imobile3.com/D5099