adde LOCK_EX to all file writes

git-svn-id: https://plugins.svn.wordpress.org/wordfence/branches/matt@1057230 b8457f37-d9ea-0310-8a92-e5e31aec5664
added LOCK_EX to file writes - merge to vtrunk

git-svn-id: https://plugins.svn.wordpress.org/wordfence/branches/vtrunk@1057231 b8457f37-d9ea-0310-8a92-e5e31aec5664