Update project setup

I noticed that your project does not include the Gradle wrapper. This is mandatory to ensure reproducible builds and working environments on multiple machines. By this you can also have multiple version of Gradle in different projects on the same computer. The Gradle wrapper makes you independent of the global Gradle installation of your system.
I added the required files for Gradle 2.1. (although I have no clue which version you are using).

Further, do not add IDE specific files to your repository since those files change a lot and there is no benefit from having them under version control. Whenever you import the project in IntelliJ or Android Studio all IDE specific files will be generated automatically. Please note that I **deleted** the `AboutLibraries.iml` to remove it from version control. This will force you to **re-import** the project **or just copy** the file to temporary location before applying this set of commits.

Moreover, I updated the Gradle scripts to satisfy the deprecation warnings. I simplified the rewrite snippet - please check.