add support for envdir
ensure envdir file is not a directory
allow function for values
Merge branch 'tonylukasavage-function_values'

* tonylukasavage-function_values:
  allow function for values
Merge branch 'master' of https://github.com/sjhewitt/grunt-env into sjhewitt-master

* 'master' of https://github.com/sjhewitt/grunt-env:
  ensure envdir file is not a directory
  add support for envdir

Conflicts:
	Gruntfile.js