Change pending snapshot to 6.0.

git-svn-id: http://libphonenumber.googlecode.com/svn@651 ee073f10-1060-11df-b6a4-87a95322a99c
[maven-release-plugin] prepare release libphonenumber-6.0

git-svn-id: http://libphonenumber.googlecode.com/svn@652 ee073f10-1060-11df-b6a4-87a95322a99c
[maven-release-plugin]  copy for tag libphonenumber-6.0

git-svn-id: http://libphonenumber.googlecode.com/svn@653 ee073f10-1060-11df-b6a4-87a95322a99c
[maven-release-plugin] prepare for next development iteration

git-svn-id: http://libphonenumber.googlecode.com/svn@654 ee073f10-1060-11df-b6a4-87a95322a99c