Upgrading to roaring 0.4.5 (bug fix release)

I recommend upgrading roaring to 0.4.5 as it fixes a rarely occurring bug in iterators (that would otherwise throw an unwarranted exception). The upgrade should have no other consequence.

Author: Daniel Lemire <lemire@gmail.com>

Closes #3044 from lemire/master and squashes the following commits:

54018c5 [Daniel Lemire] Recommended update to roaring 0.4.5 (bug fix release)
048933e [Daniel Lemire] Merge remote-tracking branch 'upstream/master'
431f3a0 [Daniel Lemire] Recommended bug fix release
[SPARK-4142][GraphX] Default numEdgePartitions

Changing the default number of edge partitions to match spark parallelism.

Author: Joseph E. Gonzalez <joseph.e.gonzalez@gmail.com>

Closes #3006 from jegonzal/default_partitions and squashes the following commits:

a9a5c4f [Joseph E. Gonzalez] Changing the default number of edge partitions to match spark parallelism
[SPARK-4115][GraphX] Add overrided count for edge counting of EdgeRDD.

Accumulate sizes of all the EdgePartitions just like the VertexRDD.

Author: luluorta <luluorta@gmail.com>

Closes #2975 from luluorta/graph-edge-count and squashes the following commits:

86ef0e5 [luluorta] Add overrided count for edge counting of EdgeRDD.