better looking

##### adapt `solarized` theme for iterm2 and vim
* iterm2
  * http://iterm2colorschemes.com/

##### adapt better airline theme and enable the powerline font for airline
* enable powerline
  * https://coderwall.com/p/yiot4q
  * http://oooooooo.hatenablog.com/entry/2013/05/01/151455