removing the dependency on jquery. Using es6

[widged]

Sending a pull request, to follow up on #85

[coveralls]

Coverage remained the same at 87.324% when pulling 3bdc1bd on widged:master into 9570932 on JuliaWeb:master.

[hustf]

We will drop Julia 0.5 support now, in a separate pr before tagging a new version.
The Julia 0.6 win32 failure is interesting. One of the browsers failed to respond in the same way as before. Will look more closely on the appveyor logs.

[hustf]

This removes some deprecation warnings in Firefox. The style is unfamiliar but we need to keep up with the times.

The behaviour in IE 11 is confusing. Could you additionaly push some warning for those with old browsers? Here's one recipe:
https://stackoverflow.com/questions/29046635/javascript-es6-cross-browser-detection

[hustf]

Tried to rerun appveyor tests a couple of times.
Possible explanation for the failure in appveyor:
Chrome is launced first, firefox second. There's an 8 seconds pause in between, yet Firefox opens the first websocket. Chrome is usually slower than Firefox. Also, chrome is slower because of Julia compile times on the first run. Thus, a chrome and a firefox sockets are assigned the same socket number by the underlying software.
A solution may be to switch the order of testing Chrome and Firefox here. This is of course irrelevant to this PR, but we won't tag a new version before the tests consistently pass.

[coveralls]

Coverage remained the same at 87.324% when pulling 3bdc1bd on widged:master into 9570932 on JuliaWeb:master.