Update to latest bootstrap script, v2014.08.23

* Avoid redirect breakage when installing EPEL with rpm on RHEL 5
* Ensure python-apt is installed by the bootstrap script for Debian & Ubuntu minions. Thanks @garethgreenaway.
* Don't shallow clone on git versions lower than 1.7.10
* Only shallow clone on git tag based installations
* Configurable Salt repository clone directory for git based installations
* Distro Support Fixed:
  * Fixed the URL to download EPEL for Cent 5
  * Use the full path to the `chkconfig` binary when checking for services in SysV init systems.
  * Fixed an issue where the default sleep period(3 secs) on Ubuntu would cause a race condition with upstart wherein the package installation would call an upstart start and before it could complete, bootstrap would call another. The result was *two* copies of salt running which ended up causing a most stubborn bug that's documented in saltstack/salt#12248