Basic file overwrite detection.

Works when I try to install modules. Hooray!
CKAN.dll: Remove deprecated InstallComponent!

Nothing uses this any more, and so it can be safely removed. Hooray!
Updated tests for CopyZipEntry.

Includes explicit tests for #208.
Better handling and decoration of krakens on file overwrite.

Also, these log messages must rock if people don't know our exceptions
are called krakens.
Registry fields are now more private.

This is such a relief to me.
AvailableModule has more privacy. Huzzah!
Our registry now keeps track of which files belong to which module.

We also do consistency checks on install and un-install, and the
registry will auto-upgrade older vesions with this information, because
it's a badass. :)
Decorate FileExistsKrakens with the file owner as well.
It's no longer an error for two mods to claim the same directory.

Plus, our code will remove the directory when the lost mod using it is
removed. Pretty cool, eh?
Merge pull request #263 from pjf/208_file_overwrites

Consistency checks and file overwrite prevention.