- Replace uses of deprecated Bourbon helpers with raw CSS
- Add autoprefixer into the build chain to prefix the now removed helpers
This process was achieved by running through each of the deprecation warnings and using the following bash function to replace it in all files:
```
function bourbon-deprecate() {
grep -rl "@include $1" ./frontend --exclude-dir=.git | xargs sed -i '' -E "s/@include $1[(](.*)[)]/$1: \1/g"
}
```
For some helpers, this did not result in valid CSS, so manual modifications were made.
Closes#1189#1274
Use the [SockJS Protocol](https://github.com/sockjs/sockjs-protocol) to handle
bidirectional communication instead of plain websockets. This allows
distributed queries to function in situations in which they previously failed
(Load balancers not supporting websockets, issues with Safari and self-signed
certs, etc.).
Also includes fixes to the JS message handling logic where slightly different
message delivery semantics (when using XHR) were exposing bugs.
Fixes#1241, #1327.
