Upgrade project to use gradle 3

[bradley-curran]

This PR is to use gradle 3.0 in our sample app.

Upgrading to gradle 3 required the following changes:

• compile keyword has changed to implementation in build.gradle
• androidTestCompile has changed to androidTestImplementation in build.gradle
• The butterknife library required an upgrade to version 8.0
• The butterknife annotations and API had changed names from inject to bind