Add gitignore for Maven, Eclipse, IDEA, and OSX files.
Add gitignore for Maven, Eclipse, IDEA, and OSX files.

google/gson,testcenter/gson,DanySK/gson-extras,todoooo/gson,mbrukman/gson,DanySK/gson-extras,mbrukman/gson,DanySK/gson-extras,mbrukman/gson,testcenter/gson,todoooo/gson,gv2011/jsoncore,todoooo/gson,testcenter/gson