* actual interface
** config KEY=VAL...
** pull-url PATH => URL
** push-url PATH => URL
** get-meta PATH => KEY=VAL\n...
** set-meta PATH KEY=VAL...
** repo-mode => active|passive
* ruby interface
** capabilities: .capabilities() => array
   Returns an array of arrays.  Each item in the array is an array of
   tokens that make a line.
** create: .create(id string, meta map) => TODO
** get-meta: .get_meta() => map
** set-meta: .set_meta(map) => map
   Returns the same as `get-meta`
** <EOF>: .finish()