Integrate JBrowse.

Included for testing:
* MAKER2 generated gene prediction in GFF3 format for two scaffolds of fire ant
  genome.
* Gene prediction for the two scaffolds of fire ant genome in JB/JSON format.
  (NOTE: instead of being a part of the repository, these should be generated
  by Ruby equivalent of JB's Perl scripts)

If you symlink data/jb/ into jbrowse/, then run `python -m SimpleHTTPServer`
from jbrowse/, then visit localhost:8000, you will see a working instance of
JBrowse.

TODO:
* JB and supporting Dojo libraries go into app/src/vendor.
  * In the first step this will be accomplished by symlinking into
    app/src/vendor from jbrowse/src.
  * Everything in app/src/vendor should be loadable with RequireJS.
  * In the second step we will move to jspm.io.
* Rename data/evidence -> data/ev
* Rename data/jbrowse  -> data/jb
* Rewrite JB's Perl scripts in Ruby (ev -> jb).
* Task model
  * Sequel migrations for tasks table.
  * Task model
  * Script to populate tasks table from ev (ev -> pg)
* /curate
  * nav bar on top with user name and logout button
  * Task UI after nav bar: get the location of a task's JSON from server and
    call new Viewer() with it.  new Viewer() will require and initialize JB.
  * Next button at the bottom.  Clicking Next redoes the step above.
* Include a BAM file for testing.

Signed-off-by: Anurag Priyam <anurag08priyam@gmail.com>