Braincase should be locked when backing up

[bhavicp]

When backing up, Braincase should be 'locked' and signaled in a polite way.

[bhavicp]

This needs to verified that it's actually needed, as no known database tables are currently in use which could go to an inconsistent state.

[hamstar]

I would argue against locking the system. We should use rsync to copy the files to another location because rsync can copy files that are in use. Then tar up those files.

Even without this, the backup process is so quick that the amount of data that would be lost not backed up by not locking before backing up would be negligible.

Even if some data was not backed up, it would still be backed up in another 24 hours so is still within the requirements.

We would of course exclude things like the dokuwiki cache and lockfiles from the backup.

[hamstar]

This doesn't need to happen... we can workaround this using the methods specified in #272.