Remove fuse dependency from encfs

As of https://github.com/Homebrew/homebrew/commit/35391ad88edfa20f770cfd4ffc7ad1d9fe0d58f6

Boxen encfs prefers osxfuse rather than fuse4x. This means that people
can’t configure fuse (and thus use encfs to access credentials).

A fair amount of head-scratching, including poking around with `otool`
and the like to diagnose

```
dyld: Library not loaded: /opt/boxen/homebrew/lib/libosxfuse_i64.2.dylib
  Referenced from: /opt/boxen/homebrew/bin/encfs
  Reason: image not found
Trace/BPT trap: 5
``` 

Comments welcome as to whether a puppet module to do the commands would
be useful – https://github.com/Homebrew/homebrew/blob/22549f45b231e82960cd5f51fe2489cae5b63a11/Library/Formula/osxfuse.rb#L44-L45
Remove fuse module entirely

It is no longer used by encfs and no-one uses it independently. See
@jabley notes on 4a2e5e6 for more details of why encfs no longer needs
this.
Merge pull request #93 from alphagov/update-encfs

Remove fuse dependency from encfs