3644: Switched around command line parameters a bit.  Will default to --home
now.  Renamed GroupsDirectory to HomeDirectory and GroupDirectory to
ProjectDirectory.
3644: More renaming GroupDirectory to ProjectDirectory, removing name links.
3644: Working on adding timestamps
3644: Project and Home directory work.  Added support for returning correct
timestamps on projects, collections, files.  Should be update
CollectionDirectory if the underlying collection record changes.  Fixed bugs.
3644: build_project_trees method ported from workbench, needs testing
3644: Shared project list almost works, still debugging.
3644: HomeDirectory and ProjectDirectories work, added filename sanitization.
3644: Collections work again, added .portable_data_hash and .manifest_text
virtual files to detect if a directory is a collection.
3644: Re-added support for files with json contents of arvados objects.
Changed block size reported by getattr() use 512 byte blocks which is seems to
be necessary to get 'du' to compute the right results.
3644: Default mount mode now includes home, shared, by_hash, and by_tag.
3644: Tested, fixed various mount modes.
3644: Tweak CollectionReader manifest text regular expression to use multiline
match.
3644: Add threadsafe arvados api access.  arv-mount now releases llfuse global
lock when performing network requests.
3644: Change metafiles to .arvados#collection and .arvados#project.  Change
--by-hash to be --by-id since it works with both uuids and portable data
hashes.
3644: Added choose-your-own-adventure README files to the --all and --by-id
directories.  Regular expressions are now compiled once at the top for
efficiency and readability.
3644: Add --by-id to invocation of arv-mount in crunch-job to get the same
behavior as before.
3644: fuse_arvados test pass.
3644: Changed so ctime == mtime because ctime is not creation time (arg!).
Added atime.  Tweaked timestamps behavior be a bit more useful.
3644: minor control block indentation fix.
3644: Restore 'tag' tests and add 'SharedDirectory' and 'HomeDirectory' tests.
All tests should pass now.