Use BufferedProcess wrapper

For #13 :
I got something working.  I used the atom module `BufferedProcess` [1] that I saw being used by the *run-command* package [2].  It is a wrapper for child process with stdout/stderr variables.

You can take over or I will work on it more later today/tommorrow.

`Ctrl-c` is just a temp keymap right?  `Ctrl-shift-c` would be better.

Also, it appears we can substitute a different shell if we are not using bash.

[1] https://github.com/atom/atom/blob/a24d1d1af7a601302b80161ec452680c29ec0ad3/src/buffered-process.coffee
[2] https://github.com/kylewlacy/run-command