Added class parameter for external templates and tests

[solarkennedy]

In the readme it says you can do this:

class { 'motd':
  template => template('mymodule/mytemplate.erb'),
}

But unless I'm missing something, I don't see a class parameter that allows that?

This pull request adds that feature, so I can use this module with my own templates without modifying the module in any way!

[daniellawrence]

👍

[kian]

👍 I would use this feature as well. Would love to delete my personal fork.

[mlocher]

👍

[solarkennedy]

This silly module may be very far down on @puppetlabs todo list :)

[mlocher]

Probably, in the end I used your branch, but it's still the most downloaded one on the puppet forge.

[apenney]

No module is too small for us!