Auto merge of #1659 - alexcrichton:shorten-paths-on-windows, r=alexcrichton

Unfortunately paths are getting a little too long on Windows and libgit2 is
given us back the error:

      Failed to rename lockfile to 'C:/bot/slave/nightly-dist-cargo-win-gnu-64-64/build/target/x86_64-pc-windows-gnu/debug/cit/test-155/home/.cargo/git/checkouts/meta-dep-27104ee87001fd00/08c585f6f3927118da012a2d682b67a789c35211/.git/objects/pack/pack-ba5fd201f4c1be9792e6d54eef194e6b733ae719.idx': The data area passed to a system call is too small.

Windows isn't always the best at handling long paths, so this commit changes the
location of the `cit` output directory where tests are located as well as
shortening the name of each test's folder to hopefully get the folder sizes a
little under the limit.

I believe this test is only failing on the nightly bots because the folder name
for the nightly bots is longer than the folder name for the auto bots. Hurray!