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
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.
cAdvisor version 0.5.0
Merge pull request #284 from vmarmol/release

cAdvisor version 0.5.0
Update libcontainer for new net stats patch that uses less CPU.
Merge pull request #285 from vmarmol/master

Update libcontainer for new net stats patch that uses less CPU.
Only overwrite the Name and Parent in the libcontainer Cgroup.

Fixes #287
Merge pull request #288 from vmarmol/limits

Only overwrite the Name and Parent in the libcontainer Cgroup.
Fix logic for deciding if Docker container was not found.

This is currently broken for all searches of Docker containers.
Merge pull request #289 from vmarmol/docker

Fix logic for deciding if Docker container was not found.