rename exec to run. exec is a method of Kernel
add ssh_key config

if present GIT_SSH and GIT_SSH_KEY are set in env
to make git use provided ssh key
DDL string values need a maxlength.

Found by trying mco plugin package - but we clearly need an rspec test which loads
and validates that the DDL is workable too.
The string 'false' which is what we get from the config file is a true value in ruby
Ability to ignore specific branches
Make the ssh wrapper script dynamically if needed. Kinda a gross hack, but mco plugin package can't easily take our .sh with us
Update the application to make you specify a parameter
Changes to have to pass a branch to update, but not have to pass a revision
We actually want / in branches, so that we can support per user branching
Only alphanumeric characters, so _ is allowed, but - not. Huh?
More bug fixes
Add a hook to run a script after checkout