Moved punctuation substitutions out to a module
Refactored substitutions to share code via a substitutor parent class
Moved the spell check code out to a series of substitutors based on
function

Also got rid of any spelling corrections - I don't believe that's
something we should correct for, as the potential spelling mistakes are infinite
Refactored out the remove uneccessary words method
Replaced standardize days with a weekday substitutor
Refactored standardize months out to a substitutor
Refactored standardize_numbers out to a substitutor
Moved standardize am pm into the time substitutor
Moved hyphen substitution into the punctuation substitutor
Inlined the insert space at end method
Made the insert recurs before into a regexp in a substitution, rather
than a "lame" method