Re-introduce watchman + CLI flags: noWatchman / esprintDebug

[christianvuerings]

We saw the following exception when trying to run esprint locally without watchman:

Initializingevents.js:292
      throw er; // Unhandled 'error' event
      ^

Error: EMFILE: too many open files, watch
    at FSEvent.FSWatcher._handle.onchange (internal/fs/watchers.js:178:28)
Emitted 'error' event on NodeWatcher instance at:
    at NodeWatcher.checkedEmitError (/Users/cvuerings/code/esprint/node_modules/sane/src/node_watcher.js:143:12)
    at FSWatcher.emit (events.js:315:20)
    at FSEvent.FSWatcher._handle.onchange (internal/fs/watchers.js:184:12) {
  errno: -24,
  syscall: 'watch',
  code: 'EMFILE',
  filename: null
}
/Users/cvuerings/code/esprint/build/Client.js:37
          throw error;
          ^

Error: read ECONNRESET
    at TCP.onStreamRead (internal/stream_base_commons.js:209:20) {
  errno: -54,
  code: 'ECONNRESET',
  syscall: 'read'
}

So re-introducing watchman & add esprintDebug and noWatchman options to our list of CLI flags