awesome: update & cleanup

rc
* clean layouts
* change browser to dwb

functions
* update mwidget_arrow to accept tables of symbols and fg/bg colors
* volume widget works with a gradient now

widgets_custom
* use new mwidget_arrow function
* add gradient to volume bar
* use builtin os.date instead of executing date

widgets_main
* use new arrow function

themes/solarized
* change font to Inconsolata
* change systray background color