Warn user if JS is not available

[ultima]

I propose to display a visible warning to the user if no javascript is detected and the active skin requires JS.

The default-shipped skins (both Larry and Classic) do not work at all if javascript is disabled on the client machine. See ticket:1488614 about what happens in that case. Users who experience this issue are currently left without a clue about what could be wrong, even though this could be easily detected by RoundCube.

Example message: "Warning: Javascript support is required for the current webmail interface, but no javascript could be detected."

[aberglund]

I've added this to the login.html template for several versions, probably back as far as 0.4. Pretty simple, this is my addition:

<noscript>
<div id="javascript">
<div id="javascript-header">
<p><strong>If you see this message, Javascript has been disabled in or is not supported by your browser. </strong></p>
</div><div id="javascript-body">
<p><strong>This webmail interface requires Javascript. If you are seeing this message on a district computer, contact your technology support team for assistance.</p>
<p>If you are seeing it on a non-district computer, it is recommended you update your browser or re-enable Javascript for full functionality.</p>
<p>If using Javascript is not possible, use Webmail Basic (link below this login box).</strong></p>
</div>
<!-- #javascript -->
</div>
</noscript>

[thomasb]

Added in commit [b6add5aed0cfe]