Revert 214177 "Use plain sh instead of bash in the git template ..."

Revert 214177 "Use plain sh instead of bash in the git template ..."

> Use plain sh instead of bash in the git template hooks.
> 
> The scripts are simple enough and should work fine under any POSIX shell,
> which is particularly helpful when one is using `gclient sync' on a platform
> that does not have /bin/bash (ie. it's installed in another location or not
> present at all), since the hooks are automatically added to the git
> checkouts.
> 
> While here, just `exec' the scripts directly instead of invoking another
> shell by hand and remove the redundant `exit 0' lines.
> 
> R=cmp@chromium.org,dpranke@chromium.org,szager@chromium.org

TBR=raphael.kubo.da.costa@intel.com

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=214178

[Isaac (away), 2013-07-29 12:09:57]

Committed patchset #1 manually as r214178.