update version datestamp for June 2013 release

git-svn-id: http://google-cache-invalidation-api.googlecode.com/svn/trunk/src/google@307 1cc9d426-c294-39be-ba72-c0199ca0f247
1 file changed
tree: c9e7fe888cadcc7f3ab64d1f13f6ff98c608ab15
  1. cacheinvalidation/