[POM] Bumped up Spark version to 1.5.1.
[POM] Bumped up Spark version to 1.5.1.

emmalanguage/emma,joroKr21/emma,aalexandrov/emma,aalexandrov/emma,emmalanguage/emma,emmalanguage/emma,joroKr21/emma,emmalanguage/emma,joroKr21/emma,joroKr21/emma,emmalanguage/emma,joroKr21/emma,aalexandrov/emma