Modify the layout of LoginActivity
Sign in / Register buttons :
- now have the same lenght
- are horizontaly align
Merge pull request #1 from radicalpixel/align_button_login_activity

Modify the layout of LoginActivity
Remove redundant Gradle settings
Set min SDK version to 8 as required for Volley
Move app code to GTG subfolder to include a top-level project
Include Volley as dependency
Setup Volley request queue (refs #2)
Implement the Login method (refs #2)
Integrate Login method (fix #2)