1014660 - Add command line parsers for numerics & booleans that return empty strings for empty values because None is interpreted by the rest api as having the value not specified
Update the users of the parsers to use versions that return empty strings instead of None for non-specified boolean & integer values
Fix PEP 8 line spacing
Merge pull request #652 from pulp/barnabycourt-1014660

1014660 - Update command line parsers to allow empty string values to clear boolean & numeric parameters