Fix of checking whether file was modified
- in case it was modified elsewhere and copied (CreationTime > LastWriteTime)
- internally DateTime in UTC (faster)

git-tfs-id: [http://falcon:8080/tfs/Projects]$/Phalanger/Main;C4954
fix of checking whether dynamic wrapper is up to date
- in case creation time is greater than last write time

git-tfs-id: [http://falcon:8080/tfs/Projects]$/Phalanger/Main;C4955