Added /proc/diskstats

Read disk io information from /proc/diskstats.
This will allow the user who provides partition container hints to get partition-specific io (blkio provides io for the container, but at the disk device level).
Gofmt all files
code review fixes
gofmt all files
Merge pull request #279 from ashahab-altiscale/additional-disk-stats

Added /proc/diskstats
Additional blkio stats

This adds blkio.io_wait_time, blkio.io_service_time, blkio.io_merged, and blkio.time to the api