Remove Jenkins master, reprepro and gitolite from uc role

Since we're going to have multiple underclouds (e.g. one per
environment), it doesn't make sense to stick these services to this
role, since there really should only be one of each of them.

Also, they don't really work out of the box, so it's not a big loss.
Merge pull request #249 from sorenh/strip-down-undercloud

Remove Jenkins master, reprepro and gitolite from uc role