Initial version of the challenge at
http://www.reddit.com/r/dailyprogrammer/comments/pii6j/difficult_challenge_1/
Code tidy-up.
Merge branch '1-diff-guesser'
Saving project file after removal of NumberGuesser.cs.
Updated README.md with completed challenges.
Added initial Calculator project with some unit tests for input validation.
Added details for 1 potential method to calculate working days.
Implemented actual check for working days.
Added unit tests to ensure end date > start date.
Updated README.md.
Merge pull request #3 from TimCollins/2-Easy-Calculator

2 easy calculator