Feature/hdfs save

[batizty]

• add save operation to store matrix/vector into hdfs
• add hdfs deps on build.sbt, and the hadoop version should be 2.7.2 or higher

[batizty]

@baukloze

Hi this branch was added the feature 'hdfs save', and your matrix/vector will be store into HDFS as specific HDFS path. All partitions will be store with name 'part-$index', which index range is from 1 to size.

Thanks