Change-Id: I8f26746a611e9ab955efe8b2597cc81db48fb085

This is a normal condition that complicates debugging, i.e.
when catching all NPE's.

Implement adjusting file and directory permissions for shared
repositories in JGitUtils.

Implement the methods getFilemode and setFilemode
in JnaUtils. Not using the libc names as we don't
necessarily use JNA and because it is not necessarily
a one to one mapping.

repository as if it was created with the --shared command line switch of git.

This is a massive commit which reorganizes the entire project structure
(although it is still monolithic), removes the Build classes, and
switches to Moxie, a smarter Ant build tookit based on the original
Gitblit Build classes.

The Ant build script will likely require additional fine-tuning, but
this is big step forward.

DisplayName used previously contained ONLY the last part
of ref-spec: this would have not worked when looking for 
objects with full ref-spec.

The fork mechanism clones the repository , access restrictions, and
other config options.  The app has been updated throughout to handle
personal repositories and to properly display origin/fork links.

In order to fork a repository the user account must have the #fork role,
the origin repository must permit forking, and the user account must
have standard clone permissions to the repository.

Because forking introduces a new user role no existing user accounts can
automatically begin forking a repository.  This is both a pro and a con.

Since the fork has the same access restrictions as the origin repository,
those who can access the origin may also access the fork.  This is intentional
to facilitate integration-manager workflow.  The fork owner does have the
power to completely change the access restrictions of his/her fork.

symbolic head and available heads.

Added convenience methods to JGitUtils to support retrieving available
heads as List<String>.
When resolving the symbolic head target as a String, if the head is
detached, attempt to match the commit SHA1 against the known tags, using
the most recent tag if more than one matches.
Revised error messaging to better reflect actual outcome.
Adjusted tab indexes on edit repository page to include default head combo
box.
Updated message key for default head combo box to use uppercase "HEAD".

Revised update results which are considered successful and improved error
messaging.

This allows control over the default branch after clone, which is equivalent to running:
  git symbolic-ref HEAD refs/heads/mybranch