Merge pull request #8 in ZP/z-push from feature/ZP-642-improve-getstate-debug-messages-for to develop

ZP-642 #comment log bytes read from file to log message

* commit 'f11dc946':
  Separate the calls to unserialize() and file_get_contents() so that the size of the file contents can be logged in the debug message.

(cherry picked from commit 23ac1fd3)