add command_options to glance::cache::[cleaner|pruner]

The parameter command_options allows to add options
(like config file to use) to the cron job command.
This makes it also possible to redirect the output.

Extend tests, to support different operating systems
and test parameters.

Change-Id: I12a76e742db7279eafa3f3ec3c92947ff551b782
Merge "add command_options to glance::cache::[cleaner|pruner]"