Encrypted git remotes are now possible 
using [git-remote-gcrypt](https://spwhitton.name/tech/code/git-remote-gcrypt/).

There are at least two use cases for this in the assistant:

* Storing an encrypted git repository on a local drive. **done**
* Or on a remote server. This could even allow using github. But more
  likely would be a shell server that has git-annex-shell on it so can
  also store file contents, and which is not trusted with unencrypted data.
  **done**

git-remote-gcrypt is already usable with git-annex. What's needed is
to make sure it's installed (ie, get it packaged into distros or embedded
into git-annex), and make it easy to set up from the webapp. **done**

Hmm, this will need gpg key creation, so would also be a good opportunity
to make the webapp allow using that for special remotes too.

One change is needed in git-annex core.. It currently does not support
storing encrypted files on git remotes, only on special remotes. Perhaps
the way to deal with this is to make it consider git-remote-grypt remotes
to be a special remote type? **done**
