crypto: use consistent variable names

Code cleanup: don't call a Connection object `p` in some places, `c` in
other places and `ss` in yet other places. Let's just call it `conn`.

This also fixes about a million style errors in one fell swoop.
crypto: use consistent conn object unwrapping

We use `Foo:Unwrap(args.This())` everywhere else, let's use the same
idiom for Connection::Unwrap().