Added Comparators for Region objects.

Added:
- Horiztonal comparator to sort a list of Region objects by x-value
- Vertical comparator to sort a list of Region objects by y-value
- Distance comparator to sort a list of Region objects by distance to a specific point
- JUnit test for the new comparators
Merge pull request #3 from kelthuzad/comparators

Added Comparators for Region objects.