Tournament Results: Implement Udacity code review suggestions

Implemented some code refactoring as suggested by the Udacity code review to reduce repeated code and increase code readability.

Corrected a mistake in defining the matches table. There was no primary unique key in that table, so rows could not be uniquely identified, if necessary.

Tournament Results: Support for an odd number of players

Added the extra credit feature to the Tournament Results Project of being able to support an odd number of players in a tournament.

This release was assessed by Udacity.

Tournament Results: Fixed missing step in README.md

Previous releases forgot to tell the user how to initialise the database in the README.md file. This has now been fixed.

Tournament Results Project - Rematch Avoidance

Added the extra credit feature to the Tournament Results Project of avoiding rematches between players during a tournament.

Tournament Results Project - Meets Spec Release

This release contains a completed Tournament Results project that meets the minimum specification in order to gain a passing mark from Udacity.

None of the extra credit features have been implemented. One or more of these will be implemented in a future release.