first attempt at #388
close #378
use latest release of ensime-sbt
Merge pull request #387 from fommil/sbt-0.13

Upgrade sbt and use latest release of ensime sbt plugin
Added ability to specific the host IP address and port for server to bind to. By default, now binds to the loopback address, only allowing local connections to the server.
Merge pull request #394 from fommil/travisci

continuous integration
Merge pull request #397 from fommil/server_hostport

rebased #333