Properly refresh branches.

Just calling `git reset --hard` on a branch name doesn't pull in
upstream changes.
Updated status test to be cross-shell compatible.
Disable exiting immediately for branch check.

The failing grep will cause the entire script to exit without disabling
immediate exiting.
Moved tag fetching.

In case $GIT_REV is a tag that hasn't been fetched yet.
Reimplemented git reset --hard.

This will make sure the working copy isn't dirty.
Fixed Ubuntu 12.10 bootstrapping of salt

Installs software-properties-common properly.
Moved warning to top of section.

Moved warning and added note that `sudo` is required.
Updated sample run line to have sudo.
Merge pull request #81 from jeffh/develop

Fixed the logic for installing `software-properties-common` on Ubuntu 12.10
Merge pull request #82 from rca/update_test_docs

Update test docs.

Bring more attention to the warning and mention the need to use `sudo`.
Merge pull request #80 from rca/refresh_branches

Properly refresh branches.