First commit
modify several simrank implementation and add matrix implementation
Imporve the matrix implementation of simrank
Improve matrix implementation: 1. add kryo serializer. 2. use CRS partition. 3. eliminate useless calculation
change simrank matrix to CCS storage
Convert partitions to RDD, reduce groupByKey size
Change some logic errors
Add PartitionsRDD to convert partitions to RDD
Change rdd to broadcast and reduce 1 time of shuffle
Code refactor and new test added
Simrank matrix improvements
1. Add ExternalCombineByKeyRDD to spill shuffle data to disk on reduce side.
2. Change sparse vector storage format to primitive array to reduce ser-deser memory overheaad.
3. Add PageRank like algorithm of SimRank random walk with restart implementation.
4. Add data verification mechanism for matrix multiplication implementation.
5. Delete useless RDD impls.
Code clean up and readme added
Small code refactor
Add Apache License
Add license and modify readme
Merge branch 'release-0.1' into github-master

Conflicts:
	README.md