create lwrp external_auth

[vkhatri]

allow wrapper cookbook to create external auth configuration files under /etc/salt/master.d/ using LWRP.

will submit a PR shortly.

[shortdudey123]

Since this is already done w/ attributes, what would the advantage of doubling it?

[vkhatri]

It helps to avoid attributes precedence when dealing with a complex environment.

Also, setting up attributes and overriding does not work that well when using wrapper cookbooks.

[shortdudey123]

In very complex env's i could see it being a big annoyance
Carry on :)