Fix for devices with /tmp mounted noexec

In the Tizen emulator image bundled with Tizen SDK 2.2, the /tmp file
system is mounted with the noexec option. This means that the
tizen-app.sh cannot be directly executed from there. This naturally
breaks all functionality that depends on tizen-app.sh.

The simplest fix is to prepend '/bin/sh ' to the command string. Then
tizen-app.sh will work with or without noexec mount option.

All tests passed on 'grunt test' after this patch.