Check User Input For Validity

[kb1lqc]

Per #29 the software should check for user input validity and essentially sanitize input.

[kb1lqc]

Taking some pointers from http://www.tldp.org/LDP/LG/issue83/evans.html

[kb1lqc]

Keeping open until unit testing checks the input values and until the timeout values are properly handled by argparse

[kb1lqc]

🚨 Ahh I still need to add in the baud rate values to the --help options.

[kb1lqc]

🚨 Ahh I need to accept timeouts that are floats as well!