Update admin app Ember version and update other dependencies

[GUI]

The admin app is currently using Ember 2.8. This LTS release was supported until earlier this year, and while we haven't really had any specific issues, it would be good to get on the newer 2.18 release simply from a support perspective. Another driver for upgrading is that there have been a couple Gemnasium security alerts for some buried NPM dependencies in this app, and while they haven't really been relevant (since the dependencies were only used in the local development server, and not actually in any of the deployed code), it would be good to get on a newer version of Ember so we can more easily upgrade to the patch releases.

Semi-related, it would also be a good time to upgrade some of our other software dependencies (like OpenResty, rsyslog, Elasticsearch, etc) while we're at it, just so we don't fall behind.

[GUI]

Upgraded Ember, along with all the other admin-ui dependencies in NREL/api-umbrella@0726136 The merge was larger, since I went ahead and made various updates to bring the coding style in line with Ember's newer eslint suggestions (which I like), and other tweaks like shifting some of our vestige Bower dependencies to NPM. But aside from those type of bulk changes, there didn't seem to be much in the way of actual compatibility issues.

All our other dependencies were upgraded in a few other commits, so we're now on the newer versions of nginx/OpenResty, rsyslog, gem updates, etc.