Removed Base64 references

Base64 from AndEngine AnchorCenter has been removed since Android 8  already implements it. This Commit removes the References to Base64 from TMX Library so that it can compile.
Merge pull request #14 from HarkDev/GLES2-AnchorCenter

Removed custom Base64 references.
Updated .gitignore for future Android Studio support.
Added crashlytics xml file to gitignore.