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
Add API version v1.2 with /docker endpoint.

The /docker endpoint lists all Docker containers under one unified
namespace.
Add v1.2 documentation to the README.
Merge pull request #278 from vmarmol/docker-api

Add API version v1.2 with /docker endpoint.
Additional blkio stats

This adds blkio.io_wait_time, blkio.io_service_time, blkio.io_merged, and blkio.time to the api
Output correct content-type with API responses.

Fixes #281
Merge pull request #279 from ashahab-altiscale/additional-disk-stats

Added /proc/diskstats
Merge pull request #283 from ashahab-altiscale/more-blkio-stats

Additional blkio stats
Merge pull request #282 from vmarmol/content-type

Output correct content-type with API responses.
Merge pull request #2 from google/master

Merging 0.5 changes into my master