git annex init probes for crippled filesystems, and sets direct mode, as
well as `annex.crippledfilesystem`.
Avoid manipulating permissions of files on crippled filesystems.
That would likely cause an exception to be thrown.
Very basic support in Command.Add for cripped filesystems; avoids the lock
down entirely since doing it needs both permissions and hard links.
Will make this better soon.
New setting, can be used to disable autocommit of changed files by the
assistant, while it still does data syncing and other tasks.
Also wired into webapp UI
