v6.51.0. Improvement.

- v6.51.0 August 29, 2013
	- Better upgrade `docpad upgrade` and update `docpad update` experience
		- Thanks to [drguildo](https://github.com/drguildo) and [Eduan
Lavaque](https://github.com/Greduan) for [issue
#619](https://github.com/bevry/docpad/issues/619)
	- DocPad will now run the local installation if it exists (avoid this
by using the `--global` flag)
		- Thanks to [Eduan Lavaque](https://github.com/Greduan) and
[flamingm0e](https://github.com/flamingm0e) for [issue
#620](https://github.com/bevry/docpad/issues/620)
	- Added the ability to uninstall plugins via `docpad uninstall
<pluginName>`
	- Updated dependencies