Added info.json file info about a simulation host, which includes wmt_prefix.
Fixed a bug where two users couldn't run a simulation one after another.

Fixed
=====

* No longer transfer files to host over ftp. These files must now be
  already installed on the host. This way makes for sense and the
  sftp connection was causing problems - multiple users could not
  run consecutive jobs.
Changed to run the launch command on a separate thread.

Changed
=======

* run/launch command now runs in a separate thread so that everyone
  doesn't have to wait for the simulation to complete on the remote
  host.
* run/launch now return a JSON containing info about the simulation
  (uuid, username, hostname).
Merge branch 'master' of https://github.com/csdms/wmt