Remove shared file system as a single point of failure

Removing from 0.9.185 because we haven't finished review.

We'd probably want some fairly extensive testing in several feed readers, as well as a DW and tumblr implementation to see if it does anything weird, like duplicate entries between polls. This will have to be a set up, test, post, test, walk away for at least a day, test again because of the inherent time delay in feeds.

What needs testing for this? Something to do with feeds?

This needs coordination with a bit of systems work.

The old tag directory needs to be put to one side.

I would also ensure that the squid cache cached the feeds.