Interview Q1 from Week1: social network connectivity completed.

Also moved percolate into its own folder/namespace.
Deque part of the Week2 assignment is done.
Added DequeIter, but in a Go closure sort of way, not an OO/C++ way.

Tests added for it and passing.
Completed part 2 of Wk2 assignment: RandomizedQueue

Has passing unit test
Finished the subsetk assignment for week2
Added multi-threaded (multi-goroutine) test to deque_test.

To test multiple iterators.