ChangeId.of(File) and ChangeId.write(File)

WAY-54
Merge pull request #18 in WAY/way-gdrive from WAY-54-changeid-deve-ser-persistido-no-drive to master

* commit 'cd5fbab52a93a2214a0a7c20d11abe914ad13dcf':
  ChangeId.of(File) and ChangeId.write(File)