initial commit
 - JUnit code that depends on Hamcrest copied into the org.hamcrest.junit package
 - Hamcrest's AssertThat copied into the org.hamcrest.junit package
 - Appropriate JUnit Tests also copied over and made to pass

Current code still depends on JUnit's dependency on Hamcrest (e.g. AssumptionViolatedException).  This dependency will be broken in the next commit, allowing JUnit to eventually remove its dependency on Hamcrest.
Merge branch 'master' of github.com:hamcrest/hamcrest-junit