Use the howler already in bower

instead of hardcoded git repo
Class to center images
Apply previous CSS class to center images

Splashscreen and about modal image both now properly centered without
extra no-content divs.

Also switched splashscreen image to SVG format.
Remove inline style from HTML
Replace HtmlTerm with fTelnet

It's a fork from the same author to fix some issues on Marisa's request.
Recreate fTelnet container on disconnection

Or it will keep creating new terminals.
Use local storage to save host settings