Fix race conditons in watcher tests

[saper]

We are getting test failures:

1. cli node-sass in.scss should watch the full scss dep tree for a single file:

  Uncaught AssertionError: false == true

  + expected - actual

  -false

  +true

  at Socket.<anonymous> (test/cli.js:317:9)
  at readableAddChunk (_stream_readable.js:146:16)
  at Socket.Readable.push (_stream_readable.js:110:10)
  at Pipe.onread (net.js:523:20)

[saper]

41 passing (19s)
1 pending
1 failing

1. cli node-sass in.scss should watch the full sass dep tree for a single file (sass):

  Uncaught AssertionError: 'body{background:white}\n\nbody{background:white}' == 'body{background:white}'
  + expected - actual

  -body{background:white}
  -
   body{background:white}

[xzyfer]

LGTM