renaming archive to folder.

I tried coming up with something clever, like ticket box or ticket cabinet,
but it seemed like they could add more confusion.  I stuck with Folder to keep
from being ambiguous (as archive can be)
Updating runTests to run both python2 and python3
Adding GitTktFolder and GitTktCache classes

GitTktFolder is an interface of gitshelve with some code specific to ticketing.  It is responsible for managing the local numbering system within a specific folder.
GitTktCache is a shell for a caching system.  In the future, it will store all the loaded GitTktFolders and manage the cached database.  From here, any changes will be added to the appropriate folder and the cache database.  Any queries are done from the database unless the database is out of date.  In that case, it will be reloaded based on the data in the folders.
Working on increasing gitshelve unit test coverage
Updating gitshelve and its tests
Adding List test for GitTktFolder