Add support for fastlane

[manankalra]

https://fastlane.tools

[ravidsrk]

@manankalra Can you open the PR with fastlane setup?

[manankalra]

Most of the fastlane featues are iOS specific. For Android, we need to include the following:

• screengrab (https://git.io/v7LXZ) : for taking screenshots
• supply (https://git.io/voOR6) : for automated uploading of metadata, screenshots and binaries to Google Play

For the first option, I need all the instrumention/espresso tests to pass, they're all failing. As listed in the README, I'm running ./gradlew app:connectedAndroidTest with an external device connected.

[ravidsrk]

@manankalra Can you create an issue with logs on parent repo?

This repo is just a generator using parent repo. https://github.com/androidstarters/android-starter