* Added new 'Getting Started with Testing' training to contain common
information on how to configure and run tests with Android Studio.
* Removed the obsolete 'Testing Your Activity' training.
* Deleted obsolete testing content under 'Tools > Workflow'.
* Moved accessibility testing checklist to 'Implementing accessibility'
training section.
* Moved content provider and service testing topics into a new
'Testing App Integrations' training.
* Updated the service testing training to reflect our recommended
approach of using ServiceTestRule, instead of ServiceTestCase.
* Renamed 'Testing from Other IDEs' topic to
'Testing from the Command Line' and moved it under 'Testing Tools'.
* Revised 'Testing Fundamentals' topic and moved it under 'Testing Tools'.
* Updated the landing page fo 'Best Practises for Testing' to provide a
central location for testing-related resources.
bug: 20722624
Change-Id: Ic1cbc79b48916dcae1c09bf5114ba8aef13d6f27
