get Celery task status directly instead of using djcelery

Lately doing HTTP request to djcelery.views.task_status to get
Celery task status info hasn't been working. Requests have been
timing out. So just absorb the code from that view and get
directly from Celery.
rm superfluous call to collection.repo_fetch

For some reason this often uses the wrong path but also is
unnecessary because repo_behind uses cached gitstatus data.
read configs from /etc/ddr/ddr.cfg and /etc/ddr/local.cfg

Values in local.cfg override values in ddr.cfg.
rm dangling MEDIA_BASE symlinks; better logging

In certain cases where the target for the /var/www/media/base
symlink is removed  (e.g. USB drive unmounted) without removing
the symlink, and a different store is mounted, the dangling
link needs to be removable.
click to toggle debuginfo; show complete commit info

Clicking pi symbol at lower-right shows debuginfo; clicking again
hides it.  No more having to show-source!
Debuginfo now includes complete commit hash plus branch and
commit datetime
alert user if not logged in to workbench server for API ops

Certain operations (getting new collection,entity IDs) require
that the ddr-local user have a local session but also be logged
in to the workbench server.
This commit adds code that looks at HTML during the process and
alerts the user if they appear to not be logged in.
fixes #178
mv tests from webui/tests.py to test_views.py,test_models.py
added Makefile to replace install.sh,update.sh
makefile now also installs and updates ddr-manual, serves at /doc/

Makefile now builds and updates DDR manuals and makes it
available via Nginx at SERVER/docs/.
use explicit path_abs for DDRLocalFile init to prevent guessing

DDRLocalFile will accept path_abs, path_rel as args.
It will also accept an unnamed arg, in which case it will try
to guess, and will likely fail.  Silently.
- Add admonishment to the programmer to use explicit arg.
- Use path_abs in *File._load_file_objects.
- Removed useless try/except.
This fix helps enable proper loading of git-annex files that are
absent from the filesystem (e.g. dangling symlinks).
override DDR Entity.checksums; get info from *.json if file absent

DDR.models.Entity.checksum requires that the file be physically
present in order to return a checksum.  This breaks if files exist
but are absent from the repo (e.g. have not been git-annex-gotten).
Files disappear from entity control files and entity.json files
may no longer contain hashes.

This overrides DDRLocalEntity.checksum and gets hash info from *.json
if the file is absent.
refactored DDRLocalEntity.add_file

- Now fails loudly!  Instead of trying to "be nice" and "do the
  right thing", raises exceptions if initial conditions are not
  met or if steps fail along the way.
- Files are now copied to tmp dir on same Store as repo, and only
  moved into the repo if everything looks OK.
- In case of incomplete commits, files are moved out of the repo
  and back to tmp dir.
- Added optional path arg to Entity/File.dump_json so add_file
  can write metadata files to tmp dir.
- Simplified control flow in DDRLocalFile.set_access so
  access_abs is always set.
- "not ok" messages are now correctly printed to addfile log.
Merge branch '079-addfile-refactor' into develop
Merge branch 'develop' into gitstatus-bkgnd

Conflicts:
	debian/conf/settings.py