Adds "assert_difference" as ruby test keyword

This will make "assert_difference" syntax highlighter
Improves xterm

Changes font to Monaco 11pt
Improves AA for xterm
Fixes issue where Ctrl-H didn't work in Tmux or Vim
Updates default tmux session for poject KUB
Adds vim-dispatch for asynchronised task in Vim and Tmux
Adds vim-abolish