Initial 'Run Command' commit

(Forked from philnash/ruby-quick-test)
Add RunCommandView
Update tests
Actually run commands with RunCommandView
Don't run a blank command
Add option to kill last command

Last command will be automatically killed if a new one is entered
Move stringIsBlank to new Utils class
Fix wrong method being called on CommandRunnerView
Add option to precede every command with another command

Useful for sourcing one's .bash_profile beforehand (in order to get the proper path)
Use Atom's built-in `padding` CSS class
Add option to snap command results to bottom