After this change, minSdkVersion is going to be 14 since the support library 26 isn't able to set the minSdkVersion lower than 14.

Also findViewById now requires type inference. Modified the code that uses findViewById.

This is a workaround to fix the continuous ci failures.

Broaden OS levels to test.

Remove the gcloud installation part during a build is running

- Android gradle tool to 2.2.0
- Support library to 24.2.1
- Rename the androidTest apk for sending it to Cloud Test Lab
  to accomodate the latest build artifact rule

Change-Id: Id0fdf8b4168db776675ef82016fa61ae6e50280f

Because from the forked PRs, environment variables set from the Circle CI UI
aren't visible. Thus service account key can't be exported.

Change-Id: I018b3300b23ead0007ea3e2574df303c7b0d5b5f

Change-Id: Iac2816198a2b9a694f2ca0a1ec302a0ebd5de4ba

Change-Id: Ie91c41555312e6ffcf5a8ef56fec0aa890778a27