Added an implemention of ArrayDeque, as well as unit tests
I also used this opportunity to reduce code duplication around other queue/deque implementations.
Removing unit test where avian implementation is more readily willing to throw a ConcurrentModificationException.
Renamed these two files to indicate they are not actual tests, but rather just to help other tests
Merge pull request #204 from jentfoo/ArrayDeque

Added an implemention of ArrayDeque, as well as unit tests