Update Select2 to 4.0.13 (and jQuery to 3.1.5, fixes #65)

[hartwork]

Fixes #65

[coveralls]

Coverage remained the same at 100.0% when pulling bbf0bed on hartwork:issue-65-update-select2 into 0a87c50 on asyncee:master.

[asyncee]

I will merge that PR because it looks good to me.

[asyncee]

This fix will be unreleased until i (or someone else) will test it.

[hartwork]

This fix will be unreleased until i (or someone else) will test it.

@leibowitz @kevin-brown @jaikanthjay46 do you have a minute to confirm that things are still working on master?

[leibowitz]

at first glance, all looking fine 👍

[asyncee]

I have merged #67, #69, #70, #72, #73, #74 in last few days because those PRs were small, simple and valuable. Sadly i have no time right now to test all those changes before release.

If someone can confirm that everything is fine on latest Django, i will be happy to make new release.