Support skins

[dandv]

Webix has just announced that a Material Design theme is in the works:

The Atmosphere package is large enough that meteor displays a progress bar while downloading it, so perhaps separate packages in the webix namespace are the best solution.

[mkozhukh]

Probably it has sense to organize skins as separate packages which will depend on base Webix UI packages. Currently each skins is a separate css file. Same will be for oncoming Material skin - it will be just one more css file and few font files.

[dandv]

Added a bunch of skins as separate packages:

• flat
• material-design
• compact
• touch
• metro
• glamour
• light
• web

There are more skins to add but I'll wait to see if the material-design skin gets moved to the Webix repo. If so, we could have only one repo for all skins, instead of separate repos all includingwebix-hub/tracker as a submodule.

@mkozhukh: there's a problem with Font Awesome: skins load it via font-face from ../../fonts/fontawesome-webfont.*, but Meteor already has an official Font Awesome package.