browser: hard-wire node-sass 1.0.3

Stick to node-sass@1.0.3 to avoid RedHat problem:

"Error: /lib64/libstdc++.so.6: version GLIBCXX_3.4.18' not found"

Watch https://github.com/sass/node-sass/issues/517 for news on long-term
solution.
browser: save reference to istanbul by `port` rather than `"istanbul"`

By using `port` to hold a reference to running istanbul servers, we can
control them independently.
browser: display correct port for app in `gulp run`

Render correct option for port of web application in `gulp run` menu.
browser: `gulp run` (re)starts servers after tests

`gulp run` startts web app, unit testing and coverage servers after
unit tests are complete.
browser: pre-install lodash so that it is available on time

npm bug seems to be causing install/postinstall scripts to run before
all dependencies are available. In particular, lodash is not available
for sauce-connect-launcher's script.

Use a preinstall script to instigate npm install of lodash to ensure
it is ready before install/post-install time.

Track these issue for long term solution:

* https://github.com/bermi/sauce-connect-launcher/issues/42
* https://github.com/npm/npm/issues/6624
browser: load highcharts up front

Load highcharts.js as an initial dependency to work around Linux issue
with availability when loading explore state.