Fix a bug that kept file.exists always true

#408
v6.21.8. Bugfix. Improvement.

- v6.21.8 February 5, 2013
	- Swapped out underscore dependency for lodash
	- Underscore is no longer provided to testers
	- `File::getMeta` now alises to `File.getMeta().get` if arguments have
been supplied
	- No longer does deep clones on template data per file render (just
shallow clone now)
	- Fixed a bug that keeps `exists` attribute on `File` always `true`
		- Thanks to [Stefan](https://github.com/stegrams) for [pull request
	- Updated dependencies
		- [bal-util](https://github.com/balupton/bal-util) from ~1.16.3 to
~1.16.3
		- [watchr](https://github.com/bevry/watchr) from ~2.3.3 to ~2.3.4
			- Way better performance and reliability
Updated dependency versions
Completely ignore growl failures. Ignore but report watching failures.
v6.21.9. Bugfix. Improvement.

- v6.21.9 February 6, 2013
	- We now completely ignore growl failures
	- We now alert the user of watch failures but still ignore them
overall (as to not bring down the entire app)
	- Updated dependencies
		- [growl](https://github.com/visionmedia/node-growl) from ~1.6.1 to
~1.7.0
		- [express](https://github.com/visionmedia/express) from ~3.0.6 to
~3.1.0
		- [watchr](https://github.com/bevry/watchr) from ~2.3.4 to ~2.3.5
			- Fixes a bug with uncaught watching exceptions
v6.21.10. Bugfix. Improvement.

- v6.21.10 February 6, 2013
	- Updated dependencies
		- [watchr](https://github.com/bevry/watchr) from ~2.3.4 to ~2.3.7
			- Works better for projects that have a large amount of files
Emphasised specifying the `dev` branch as the integration branch
Updated use of github issues in CONTRIBUTING.md
Ref #430 - Identify anonymous users by their hash and salted MAC address

See #430 for the underlying details.
Better tester port determining. Turns out pid is prone to duplication
Clarified initial versions in History.md
Merge branch 'master' into dev-mac
Merge branch 'dev' into dev-mac
More fallbacks if mac fails
Reduce the console pause delay after collecting info

From 5 seconds to 2 seconds
v6.22.0. Improvement.

- v6.22.0 March 6, 2013
	- Better port assignment to testers -
[changeset](https://github.com/bevry/docpad/commit/244390c5d349598e35e2b
99347c8b067006aa293)
	- We now identify anonymous users (while respecting their anonymity) -
[changeset](https://github.com/bevry/docpad/commit/fb8de48d7dcfc4e9211fd
898cda91c54553c1f58)
		- Closes [#430](https://github.com/bevry/docpad/issues/430)
Merge branch 'master' into dev
Merge branch 'dev-mac' into dev
Merge branch 'master' of github.com:bevry/docpad
Merged.