Added incomplete BinaryTree interface and BinarySearchTree implementation.
Removed main() method.
Added DataStructure interface.
All existing data structures now implement the DataStructure interface.
Merge pull request #9 from mfrancis95/mike

All existing data structures now implement the DataStructure interface.
Added breadthFirstTraverse() method.
Added messages to the thrown IllegalArgumentExceptions.
Added messages to the thrown IllegalArgumentExceptions from the Queue implementations.
Fixed bug in push() where the top position will increment even if the array is full.
Added a capacity check to the constructor.
Slight method ordering change.
Merge pull request #13 from mfrancis95/mike

Random changes
Merge branch 'master' into ross