(MODULES-1231) Fix apt::force locale issues

The current $install_check variable greps for 'Installed' or
'Candidate', which means that it will give the wrong result
when a non-English locale is used. This patch ensures that the
check will work properly for non-English locales by setting the
environment parameters for the exec to LC_ALL=C LANG=C
Merge pull request #394 from juniorsysadmin/apt-force-locale-fixes

(MODULES-1231) Fix apt::force locale issues