Move to rustdoc instead of ruby's middleman

* All markdown files are now rendered with `rustdoc` into HTML
* A JS syntax highlighter, prism, is included for TOML syntax highlighting.
* A new makefile target, `make doc`, will build docs into `target/doc`
auto merge of #550 : alexcrichton/cargo/rustdoc, r=brson

* All markdown files are now rendered with `rustdoc` into HTML
* A JS syntax highlighter, prism, is included for TOML syntax highlighting.
* A new makefile target, `make doc`, will build docs into `target/doc`

preview: http://people.mozilla.org/~acrichton/crates.io/doc/

Closes #524
Fix build break by upgrading git2-rs

Update git2-rs to the latest version which includes a fix for `extern crate`
syntax changes.  This version changes the interface for credential callbacks,
so update the git source provider code as well.
Fix obsolete `extern crate` syntax in some of the tests
Don't print `Running` for commands that aren't run

Also print the commands only right before they're actually run.

Closes #215
Update snapshots.txt
auto merge of #554 : bkoropoff/cargo/update-git2, r=alexcrichton

This is pretty simple.  Do the existing unit tests sufficiently cover the git2-related changes?
Always rebuild dist dir in "make dist" or install
auto merge of #559 : mbrubeck/cargo/make-install-fix, r=alexcrichton

This fixes an issue where `make dist` incorrectly does nothing after the source has changed and been rebuilt.  It also prevents `make install` from installing outdated files from the `dist` directory.
Allows bootstrapping win64 from win32 snapshot.
Remove triple = 'i686-pc-mingw32' once win64 snapshot is made.

Signed-off-by: Peter Atashian <retep998@gmail.com>
Merge commit '314d47749a79d0382eea1b710456b038a1ac84c0' into win64
Switch the URL from which nightlies are downloaded
auto merge of #562 : alexcrichton/cargo/win64, r=alexcrichton
Update "Contributing to the Docs"
auto merge of #555 : alexcrichton/cargo/issue-215, r=brson

Also print the commands only right before they're actually run.

Closes #215
Center main content in Safari
auto merge of #567 : EduardoBautista/cargo/fix-centering-on-safari, r=alexcrichton

The website is not centered in Safari.
Fix `make dist` and distcheck breakage

Fixes a regression from #559.
auto merge of #568 : mbrubeck/cargo/dist-fix, r=alexcrichton

Fixes a regression from #559.
Update all dependencies

This fixes some breaking changes with git2-rs, fixes a bug in tarball generation
from tar-rs, and fixes warnings with flate2-rs