Add Material buttons in Sign up/ Sign In layouts

Objective

While Signing up or singing in the buttons are of old style. The objective of this task to improve the layout of buttons in this.

Requirements

• Clone the source code and run app in Android Studio
• Browse the signup screen and fix the issue
• Open Pull request on GitHub, merged PR will be considered as success

Expected Outcome

A good design of buttons. One example as shown in the below mockup. Feel free for other design. For example, browse the flow of adding gmail account in Android.

Link

https://github.com/xwiki-contrib/android-authenticator