This allows custom implementations to store their settings alongside the
Gitblit GO or WAR settings while remaining unit-testable.

If an object id was not specified Gitblit used HEAD to perform the
operation.  This breaks under some conditions like working with a
repository that does not have any commits on master but does have
commits on a vcs-import branch.

The new approach is to centralize the resolution of unspecified object
ids to a common method which resolves HEAD first but uses the most
recently modified branch if HEAD points to nothing.

This commit also includes a non-functional method for creating an empty
branch. I couldn't figure out how to make JGit create an orphaned
branch.

Jetty 7.4.4 introduces a fix to correct url generation. Unfortunately,
this "fix" creates a bug for resolving the root page. Evidently the bug
may really be in Wicket.

Wicket Bug: WICKET-3841
Eclipse Bug: 351199

* Build script overhaul including building & publishing GO, WAR, Docs,
and Site.
* Restored JGit 0.12.1 dependency and backported Blame.  Got tired of
waiting for JGit 1.0.0 Maven artifacts.
* Changed Summary Page layout
* Optional cookie authentication
* Added icons for log, tags, and branches panels.
* Show last commit author and short message on branches panel.
* Unit testing.
* Documentation.

Reorganization of resources. Dropped most hard-coded webapp
configuration in favor of common web.xml file. Still contemplating
configuring git servlet from web.xml too.

Replaced servlet container basic authentication with a custom servlet
filter which performs the same function.  The advantage to this is
that the servlet container is now divorced from the webapp.

The login service (realm) also simplified a great deal and removes its
Jetty dependencies.

Additionally, the basic authorization pop-up will be displayed as
needed based on the repository's access restriction.  This was
necessary for view-restricted repositories with the RSS feature.  Its
also necessary for completely open repositories as before it would
prompt for credentials.

Improved feed syndication feature.