Currently the LDAP user service will not dereference aliases when
searching for groups. This patch enables dereferencing aliases for the
group search. This is benefitial if groups are defined in the DIT in a
common place but only certain ones shall play a role in Gitblit. These
can now be linked under a group that can be provided as search base for
groups, without having to recreate the existing groups under the search
base.

In addition, the new doSearch() method implemented in this patch also
limits the attributes returned for the group search to the "cn"
attribute, which is the only one used. That prevents returning all the
members of the result groups, which can be a lot.

Change-Id: I29e1560390810304386dcea5ca40aaf78601b3a9

Change-Id: I9f91138b20219be6e3c4b28251487df262bff6cc

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.

feature: when LDAP user synchronization is enabled, one can configure GitBlit to delete all LDAP users from the backing user service that are no longer existent in LDAP. By now LDAP users that were deleted still appeared in the GitBlit user list.

By providing an URL in the format "ldap+tls://ldapserver.example.com",
you can now connect to LDAP servers that require StartTLS command.

Add code / test to defend against LDAP injection attacks.