Auto merge of rust-lang#2092 - gkoz:lock_line_endings, r=alexcrichton

Before writing the lockfile read the existing one and

 * detect the line endings style, fixes rust-lang#2076, rust-lang#1722;
 * compare the contents to avoid redundant overwriting.

auto merge of rust-lang#988 : Gekkio/cargo/zsh-run-normal-args, r=ale…

…xcrichton

Running a Rust program with some arguments such as files is a common use
case. The ZSH completion did not declare support for extra arguments to
"cargo run", so file completion was impossible. In practice pressing TAB
after writing "cargo run -- " gave no completion at all.

After this patch, cargo run can do "normal completion",
which in practice does file/directory completion. This works nicely
with "cargo run -- ".