Added an algorithm which computes the minimum s-t cut in a directed, weighted graph.
Added a unit test class for the MinSourceSinkCut class.
Added author and short class description.
Added an implementation of the Hopcroft-Karp algorithm which computes a Maximum Matching in a bipartite graph. Included unit tests as well.
Fixed first batch of comments. Added additional test to MinSourceSinkCutTest.java
Removed 2 more System.outs
Merge pull request #14 from jkinable/master

Min source-sink cut alg and Hopcroft-Karp max bipartite matching alg.
Update contributors/history for previous commits.
Add file headers to recently added files, and make computationally-expensive
HopcroftKarpBipartiteMatching input validation only run when
assertions are enabled.
Fix multiple bugs in StoerWagnerMinimumCut.

- Negative edge weights cause an exception in the constructor
- Zero edge weights work
- 0 < Weights < 1.0 work
- Multigraphs work
- Graphs with less than 2 vertices cause an exception in the constructor
- Graphs with 2 vertices work
- Removed unneeded List to conserve memory
- Constructor takes UndirectedGraph instead of WeightedGraph as weights
  are optional but directed edges are forbidden. This is an incompatible
  interface change!
Merge pull request #15 from hnridder/master

Fix multiple bugs in StoerWagnerMinimumCut
Remove System.out calls from StoerWagnerMinimumCut, add credits.