Mark "hadoop" dependency as provided

There's no need to pull in the hadoop dependency as Hadoop is always provided when you run jobs.  Excluding jars in assembly is error prone and forces downstream MR jobs to exclude the same jars.  A much better solution is to mark the hadoop dep as "provided" which means it won't be pulled in transitivitely by users of ScaMR.  It also removes the need to exclude jars in assembly.

Also I added the easy ability to publish both 2.9.1 and 2.10.0 artifacts.