Draft: verify_input function

* verify_input function to acertain user input as integer or not.
* Body of fizzbuzz function taken from Rosetta Stone, verified to be correct.
Optimizing the sanitizing function: prefering a while True loop to recursion that can blow the stackl
Implement part if user does NOT want to update any parameters.
Need to think how to implement user choosing default values if user chooses to enter parameters
Implementation of FizzBuzz challenge

* fizzbuzz() function complete
* User interaction (editing defaults? If so, entering values for required arguments) implemented but probably could be very much refactored

TODO

* Printing the part of the array per user request
* Saving results to file
Touch of refactoring... little less code
Touch of refactoring... little less code
Somewhat prettier code constructing the call to fizzbuzz() when user interacts (also, usage of zip() function and some dictionary comprehension)
Starting to sketch out the output to file mechanics.
Core fizzbuzz() functionality (including the user interaction) is down.
Few more steps toward printing result array to file
Need to get a handle on how to take the REAL path of a user input path (os.path.abspath("c:\python34\test.txt") for example gives the path as the whole string for some reason)
Solidifying code even further by refactoring similar code into a function.
Need to get the whole path thingie working -- last bit before feature is complete!
Fuck yeah!

* Feature complete and working:
** User prompted whether to edit challenge's parameters (defaulting to no)
** If user edits parameters, user input is validated
** Challenge array created in background, user prompted to print result to file (defaulting to no)
** If user chooses to export result to file, path is validated to be writeable before writing in an OS-agnostic way
** If path is un-writeable, user is prompted to enter a valid one (defaulting to <present working directory>/fizzbuzz.txt)