Fix cases where a registry is not updated

If a registry already knew about a package, but didn't know about newly
published version of a package, then the registry would occasionally not be
updated when it otherwise needed to be.
auto merge of #1067 : alexcrichton/cargo/fix-registry-update, r=alexcrichton

If a registry already knew about a package, but didn't know about newly
published version of a package, then the registry would occasionally not be
updated when it otherwise needed to be.
Move all deps to the registry
Update rust and all deps
auto merge of #1066 : alexcrichton/cargo/registry-deps, r=alexcrichton
Update to new-style rustc CLI args
auto merge of #1075 : cmr/cargo/rustc-vverbose, r=alexcrichton

Closes #1073
Use std::collections::{BTreeSet, BTreeMap} instead of std::collections::{TreeSet, TreeMap}.
Fix readme instructions for submodules
auto merge of #1078 : alexcrichton/cargo/issue-1071-readme-fix, r=alexcrichton
Merge branch 'pr-btree' of https://github.com/akiss77/cargo into akiss77-pr-btree
Update to rust master
auto merge of #1079 : alexcrichton/cargo/update-rust, r=alexcrichton

Continuation of #1077
Closes https://github.com/rust-lang/cargo/pull/1079
Merge remote-tracking branch 'upstream/master'