Remove release signature information from website

[brson]

In an ongoing effort to streamline the web site I would like to remove the signatures and the link to the signing key. I believe the integrity of the Rust distributables is not important to most users. There is a prominent previous releases link on the web site that contains everything about each release, including the signature and the keys.

@graydon what say you?

[jruderman]

Yes, it should be removed. The page and link aren't even SSL!

[brson]

I've done this without discussing with @graydon. So bold.