Clean up build files from repository

Removed ant-build and ant-gen(platforms/android/CordobaLib) from tracking files
ESTIMOTE-14 grunt task to prepare for phonegap
https://dotcreek.atlassian.net/browse/ESTIMOTE-14
Added grunt task to prepare content for android/ios build.
    grunt phonegap # will prepare content for android by default
    grunt phonegap:ios
    grunt phonegap:android