Initial mavenization, including example keystore for signing jars

All tests are passing in maven.  The jar file manifest looks good from what I can tell.  I was able to create an intellij project using the "import maven project" feature, and running tests from within intellij works just fine.

I set the version as "1.0-SNAPSHOT".  I figure when there are official releases, folks will want to branch/tag the source and edit the version accordingly.
consider making testng in scope 'provided' (or use '<optional>true</optional>') since if people really want to use the helper methods in htsjdk.samtools.SAMTestUtil, they will be able to add testng as a manual dependency, and it probably does not need to be there as a transitive dependency in the general case.