Implemented  interval tests via webui. Removed blocks in server.go from
accessing the interval and stop fields from the config generated from
the webui. Added ginkgo tests to test these fields. Added fields in
index.html to allow the user to select values for interval and stop,
defaulting to 0. Added functions to app.js to package the input into
the config that gets sent down. Added tests to test.js to ensure the
values are within acceptable bounds.
Merge pull request #38 from julz/interval_ui

Implement interval/stop experiments from the web UI