Add coverage status badge in README

Also use shields.io for flat style badges
Reorder README sections
Fix typo
Make it very clear that XCDYouTubeKit is against the YouTube ToS
Use the master branch for build and coverage status
Add platform, pod version and license badges
Update CHANGELOG
Update demo projects version to 2.0.2
Update version to 2.0.2
Merge branch 'release/2.0.2' into develop