Remove privileged proxy for converting ids between e-mail addresses

[jcscottiii]

Originally, you needed the user id to set roles. Back when this was
corrected the only way to do that was to query for the user info first
by e-mail address to get the id. Now, there are APIs that make it
possible to set roles by e-mail address. This patch removes the need
for the privileged query call.

Example of the new by Username apis to use:

[jcscottiii]

@msecret

[jcscottiii]

I figured that this is the time to do it since the ability to invite someone to an org via e-mail does not exist in the new deck. so when we finally do it, we can use the new api.

Right now, we just point people to docs.

[coveralls]

Coverage decreased (-1.9%) to 70.958% when pulling 0e218bb on remove_priv_calls into da6c5c0 on staging-alpha.