CommandExecutor enhancements

[jefflester]

The CommandExecutor class could use some updates.

• The class should have a suppress_output property. If given to the constructor as True, the executed command will direct all output to DEVNULL. Handled in commit e167625d2fc246d3423749a4fafb4f4ae3f0b7d3.
• The default of the executor should not use shell=True for everything (this is frowned upon and viewed as a potential security hazard). Look into using the shlex module to parse complex command strings and execute the statements with Popen.

[jefflester]

After messing around with shell=False and splitting the command into a list via shlex, it's looking like more complications are created than solved. I am closing this issue for the time being and will revisit it if another person raises a valid reason.