Use Project.nameKey() in lieu of Project.NameKey.parse()

Despite Gerrit allowing the creation of projects with '+' in the name,
pushing to LFS appears to fail in this case because the underlying GWTORM
methods used by NameKey.parse() replace the '+' with a ' '.  Using
Project.nameKey() resolves the problem.

Also changing the use in LfsLocksAction under the assumption that this is
incorrect as well.

Change-Id: I6defc59e9dc1a218f6a7e156c2f9fd28565f0ca9