Update BundleCheck to not use `git check-ignore`

This command was introduced in git 1.8, which doesn't come with most
CentOS systems. Change it to use `git ls-files` instead.

Change-Id: I45734234f102cae22dba6c667a30930c104fe7ff
Reviewed-on: http://gerrit.causes.com/37939
Tested-by: jenkins <jenkins@causes.com>
Reviewed-by: Shane da Silva <shane@causes.com>