fires closed.bs.alert *after* DOM detach()

fires closed.bs.alert *after* element is removed from DOM.
Previously it fired while the element was still attached.
Update alert.js

Added call to remove() after event fires to clean up data as per discussion at #12379
Improve accessibility of close buttons in modals & alerts

Adds textual caption to the close buttons. The "X" multiplication sign isn't very meaningful to screenreaders.

Credit: https://github.com/paypal/bootstrap-accessibility-plugin
Per:
    https://github.com/paypal/bootstrap-accessibility-plugin/blob/master/README.md#alert
    https://github.com/paypal/bootstrap-accessibility-plugin/blob/master/README.md#modal-dialog
document #13390
mark Android Firefox as officially supported
Wall of browser bugs: formatting tweaks
Merge pull request #13495 from twbs/android-firefox

Officially support Android Firefox
Merge pull request #13493 from twbs/close-btn-access

Improve accessibility of close buttons in modals & alerts
include RTL CSS CDN URL in Download docs
add RTL CSS files to "What's included" section of docs
import rules from Ratchet's JSCS config with which we already comply
Merge pull request #13506 from twbs/jscs-ratchet

import rules from Ratchet's JSCS config with which we already comply
Allow for resetText of a button to be a falsey value; fixes #13466
temporarily lock grunt-jscs-checker to v0.4.0

Per #13512 & https://github.com/mdevils/node-jscs/issues/357
update-shrinkwrap
bump grunt-jscs-checker to v0.4.1; refs #13512
Merge pull request #13514 from twbs/jscs

bump grunt-jscs-checker to v0.4.1
Merge pull request #13406 from EnsignR/closed.bs.alert-after-remove

fires closed.bs.alert *after* DOM detach() as per #12379
Merge pull request #13511 from hnrch02/button-reset-falsey-values-fix

Allow for resetText of a button to be a falsey value; fixes #13466
Update JSZip to v2.2.2.