New SVG assets for knobs

[paulgoetze]

Fixes #19.

Currently using these icon assets:

• Entypo+ icons by Daniel Bruce (https://github.com/adamwathan/entypo-optimized)
• Ionicons for speaker/mic/camera icons (because the sound off/on from Entypo look more like a spotlight in our context)

Both are free icon sets under CC + MIT license.

[janlelis]

Thank you, this is total awesomeness!

All the following remarks are rather smallish things: 1) Could you add a note to the bottom of the README (below the copyright line) that goes something like "Icon assets CC-BY(exact cc license + author here)" 2) I've noticed that "mute self", "turn off my camera", and share screen are also buttons which hold some state - so we probably need second pictos there too (or we'll use some css effect...). Do you have an idea? Have said this, it doesn't have priority since these features haven't landed yet, anyways. So for now, we can actually hide all three buttons (and activate them with #9 and #8) 3) The "close button" for network info and info pages is somehow not shown on my system, do you haven an idea why?

[paulgoetze]

@janlelis all done. I switched to Ionicons for sound, camera, & mic icons, because they provide the off icons, too (had to create a camera-off icon, though).

The issue with the close button was a display-flex that did work for the button in Firefox, but not in Chrome.

[janlelis]

Total awesomeness!

[janlelis]

A small follow up issue is here: #29