Jenkins SNAPSHOT deploys

[Josh Elser]

FYI, finally took a moment to enable snapshot deploys for 1.6 and 1.7 
(master) in Jenkins.

They should only deploy when the entire build is successful (not using 
`mvn deploy`, but the post-build step in Jenkins). Thanks, Billie, for 
that recommendation.

Verified that we have a new 1.7.0-SNAPSHOT as well as a 1.6.3-SNAPSHOT. 
I'll go through and do 1.5 now as well (probably only the Hadoop2 build 
since they should be the same artifacts as the Hadoop 1 build).

- Josh