Squashed commit of the following:

commit 062a0786273815400c45e7c6c3d76f38d4e2766f
Author: David Yan <david@datatorrent.com>
Date:   Tue Feb 4 10:47:20 2014 -0800

    removed unnecessary imports

commit 0dfe8461b2dcc44a2da5c2cc88c87e71dea1f3d3
Author: David Yan <david@datatorrent.com>
Date:   Tue Feb 4 10:47:07 2014 -0800

    made most dependencies of contrib optional

commit 47f837e28b942bc225be41bcee0811348497387f
Author: David Yan <david@datatorrent.com>
Date:   Tue Feb 4 10:46:51 2014 -0800

    added package-info.java to lib/db