Add numeric compare for validation

[Mabuchin]

Hi, I needed numeric compare when pre-post validate such as cpu_use,memory_available. for example, less than memory 50% is executed by commit_config.

• modified: _compare_getter_dict
• add method: compare_numeric
• add test: get_environment

[dbarrosop]

Sorry for the late response on this. Looks good so I will merge after we add a note to the documentation.

Thanks!

[Mabuchin]

Thanks! I'll add a note to the documentation and send PR right away :-)

[Mabuchin]

Sent PR to napalm #377

[dbarrosop]

Great job, thanks!