File class members are encapsulated, and internal lock was added.

A lock was added to the file class to properly handle multiple threads
accessing the self encryptor. Actual chunk storage and incrementing is
still a work in progress.

This technically completes JIRA ticket MAID-153 too.
Renamed File::IsOpen to HasBuffer. Corrected timer callback in File.
FUSE Opendir now checks for directory existence
Added test for File close timer and exceeding buffer limits.
Merge pull request #36 from vtnerd/MAID-404_FileLocking

File class members are encapsulated, and internal lock was added.