Also update to use https instead of http. This avois mixed content
degradation on docs.rs.
The doc root URLs are correct as they are, the URL does not include the
crate name itself.
For some reason, rustc 1.0.0 can't find `PrimInt` if it's before `cast`,
but later versions are fine with this. That may have been a compiler
bug that was fixed. Switching the order seems to work everywhere.
bluss
Ivan Ukhov
Josh Stone
Vinzent Steinberg
Łukasz Jan Niemier