Specify custom TERM when spawning PTYs

This produces better results when running servers inside of terminal
multiplexors. For example, a TERM of screeen-256colors will cause ZSH to
output the first argument of the input command next to the output of it.

Explicitly specifying a TERM fixes that.
Add colors configuration with config.web_console.colors
Test and change the default theme to :light
Clean lib/web_console/engine.rb spacing
Refactor web_console.process_whitelisted_ips initializer
Inline the array processing of whitelisted_ips
Tweak solarized light to match my Gnome Terminal

I don't know if this is the "right" configuration, but all my apps seems
to like it.
Add color switching ENV vars to the dummy app
Extract the colors in own files
Introduce config.web_console.font

I do have a couple of style options now, I'm gonna try and extract them
into their own ActiveSupport::OrderedOptions instance.
Extract the style options into config.web_console.style
Document and prepare for 0.4.0
Fix wrong comment wrap
Bring an updated picture back to the README

Remember this thing about the picture and the 1000 words? Its true!