Added gradle wrapper etc.

* Project can be directly imported into studio without local gradle install
* Is recommended that way AFAIK
Removed RestaurantManager

* Looks like JAVA-main class
* Not used in rest of project
Added androidannotations dependencies
Removed RestaurantActivity

* Not used outside AndroidManifest.xml
Solved "New method on old API" warning
Basic cleanup

* Removed commented out code
* Imports ".*" instead of explicit imports
Removed more unused code
Moved versioning to build.gradle
Added EActivity to MainActivity
Extracted some classes and introduced some callbacks

* Extracted anonymous inner classes to own package and classes
* Created IUpbWebView to simplify MainActivity
* Introduced some Interfaces as callbacks
Ran some standard Androidstudio checks and resolved some warning
Merge pull request #6 from ironjan/androidannotations

Androidannotations