Expose Sensei broker and cluster services through a servlet context attribute
Expose import/export from zoie.
1. Add some help functions. 2. Add signature getter. 3. Comments.
Added javadoc for SenseiBrokerExport hack
Change HashSet back to Collection.
Merge branch 'seas-sandbox' of github.com:linkedin/sensei into seas-sandbox
Merge pull request #79 from linkedin/seas-sandbox

Changes needed to support seas snapshot project.