Displays navigable path name on file and folder pages.

This change displays the name of the source file at the top of the
page. The name can be copy/pasted directly into an editor or anything
else to get to the file. Fixes
https://bugzilla.mozilla.org/show_bug.cgi?id=758628
The individual components of the path can be clicked on for
convenient navigation.
Rename dxr.wsgi to wsgi.py so we can put a simple one-liner in our per-deployment wsgi file.

Now the per-deployment wsgi file can say simply "from dxr.wsgi import application". We'd point mod_wsgi straight at the source tree's wsgi.py, except that it ends up at the end of a long path which contains the package version, and that will change.
Log tracebacks to Apache's error log.
Include more of the required resources in the MANIFEST so "setup.py install" installations can actually find their templates.

We have yet to figure out how to ship compiled plugins, like the clang one. Ref #110.
Properly fall back to the nb_jobs defined in the config file if none is specified on the dxr-build command line.
Don't make so much noise about missing lexer support while rendering HTML.
Remove nose from requirements.txt.

We need it only for tests, and it's already in tests_require.
Don't omit the config.py template from the built package.
Use setup.py test for tests so nose gets installed.
Add continuous deployment script. No self-updating of the script itself yet.
Decouple and stop hard-coding things.

* Lift up _latest_successful_build() to make testing easier.
* Allow command-line customization of just about everything.
* Take the newline-stripping out of run(). It turned out to be seldom useful--not worth the coupling.
This is about 200 chars (but only 1 line) shorter and has less "self." noise than the class-based version.
Fix bugs so the thing actually runs. Change some confusing vocab.
For now, let old versions of the deploy script deploy new versions of the code.

It may well never be worth the time, complexity, and effort to do better.

So we merge the deployment-only requirements file with the one for DXR proper, and we'll run the deployment script out of the deployed DXR venv.
Add continuous deployment support.
Quiet the git commands so they don't make cron noise.

We may have yet to quiet pip; we'll see.
Correct typo in context menu.
Fix 404 when using the "Browse folder contents" context menu item.
Include the compiled Clang plugin when doing setup.py install. Close #110.

You still have to run `make` manually first, but it's a step in the right direction.
Give config.py template a ".jinja" extension so package installation doesn't freak out trying to byte-compile it.

This knocks out one reason the continuous-deployment script is mailing me.