Add Crashlytics integration
Disable Crashlytics reporting for debug builds
Ignore a file with Crashlytics settings
Use `OnCheckedChangeListener`s instead of `OnClickListener`s
Merge pull request #311 from codeguru42/android/crashlytics

Add Crashlytics integration
Merge pull request #313 from codeguru42/android/oncheckedchangelistener

Use `OnCheckedChangeListener`s instead of `OnClickListener`s
Update API and library versions

Updated to use API 20. Cannot use API 21 yet as there is an issue with the tests when
using appcompat-v7:21.0.0.