Add missing operators to ShiftLanguage::OPERATORS
Trim Whitespace
Merge pull request #13 from zspencer/add_operators_to_shift_lang

Add operators to ShiftLanguage::Operators
Add all puzzles from http://sudokuplace.com/pdfs/4x4_easy_2.pdf
Add all puzzles from http://sudokuplace.com/pdfs/4x4_easy_1.pdf
Merge pull request #14 from zspencer/add_more_4x4_puzzles

Add more 4x4 puzzles
Extract GridBuilder, shift responsibility to the puzzle