If the pay interval is daily, payday is automatically set as the start date's weekday
Added more specs for PayrollCalculator.run
Added PayrollCalculator.not_valid_payday? to determine if a day is a valid payday
Rewrote PayrollCalculator.calculate

Added functionality for holidays. If the pay interval is daily and payday lands on a weekend, it won't add a day to the output array until the day is a valid payday. If the pay interval isn't daily, people can't get paid late so if it lands on a weekend or holiday it finds the last previous valid payday. Then it resumes the mormal schedule (ie, if payday is a Monday and it's a holiday, for one interval the payday is the previous Friday then the next interval it returns to Monday.)
Refactored the 'what to do if it's not a valid payday' logic a bit
Added some whitespace to make the output look a bit better
Added some more whitespace
Some refactoring in PayrollController#run
Added new test for PayrollController#run

Tests to make sure PayrollController#run is not called if thepay interval is daily
Made @holidays in PayrollCalculator readable and writable
Edited PayrollCalculator.not_valid_payday? for new @holidays variable
Edited tests for new @holidays variable
Added tests for readable and writable PayrollCalculator.holidays variable
Added whitespace between classes
Split one line to two in PayrollController#run because I like the way it looks better
Merge pull request #6 from RyanVerhey/quick-bugfixes

Quick bugfixes