Redmine #2675: /bin/bash is not available on all supported plaforms

The test script test/acceptance/08_commands/01_modules/003.cf.script
uses a /bin/bash shebang, and the Bash shell is not available on
stock HP-UX systems among others, preventing the test from running
properly. This commit changes bash to sh to conform with all the
other test scripts.
Merge pull request #665 from mvpel/redmine_2675

Redmine #2675: /bin/bash is not available on all supported plaforms