Revert "remove logo that wasn't being used"

This reverts commit 8ccf219ac8d27bd2222d6caef04bd61702e2fe3c.
add favourite_colour to seeds.rb
use the favourite_colour as the user highlights rather than the first letter of their username
make signup used custom-colour directive instead of inline style (issue with IE i think)
update colours to more gelati style - just playing with things
darken the question colour ever so slightly and make inputs have a black border in the control bar
changed the colours yet again... wheee
allow user to edit and update their favourite colour
bunch of css clean up
more css and directive clean up
lots and lots and lots of itty bitty little changes