Added testing for untested fractional? method
Added testing for single_fraction? and mixed_fraction? methods
Added additional tests for fractions with padding
Added separate regexes for fractions, single and mixed and beefed up the recognition of those fractions
Allow for negative denominators in single fractions only
Rearranged regex functions to pass tests for allowing negatives in denominator
Minor typo fixes
Changed the fraction type class variables to constants
Updated years, and added contributors. (Thanks guys)