small watch improvements and unit tests

[Matthew (matthewmeyer)]

• Adding basic unit tests for watch mode
• Forward date the packhost modified time stamp 10 seconds to keep the watcher from going crazy, see: Files created right before watching starts make watching go into a loop webpack/watchpack#25
• Improved the watch mode logging to make it easier see rebuilds occuring

[Matthew (matthewmeyer)]

Looks like debug is enabled and going to stderr which is a failure condition in my test. Can I change the debug config to stdout?

[Christopher Anderson (christopheranderson)]

Yeah, that's fine. It's not intentionally going to stderr, just default config.