[maven-release-plugin] prepare release gson-2.2.1
[maven-release-plugin] prepare release gson-2.2.1

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