Add NodeJS v0.10.26, make it the default v0.10
Merge pull request #31 from orionhealth/feature/node-0.10.26

Add NodeJS v0.10.26, make it the default v0.10
Add method to configure a nodenv plugin.

Exactly like rbenv we need capability to easily define a plugin to
nodenv. Usage here is for nodenv-vars and node-build.