Adding filesystem usage calculation for docker containers. This patch also includes some internal refactoring.
'machine' api now exports a list of all existing 'ext*' filesystems along with the capacity.
Avoid storage usagge calculations when aufs driver is not being used.
Merge pull request #267 from vishh/disk_usage

Add filesystem usage support for docker containers.
LXC Factory and Handler

This factory and handler can retrieve memory, cpu, diskio, and network information of lxc containers.
The handler can be passed additional container information(e.g. network interface) using a cdesc.json file
NetworkInterface now contains both VethHost and VethChild
Updated import and comments
Added network stats to raw handler

Raw handler now parses an optional json file with the network interface information, and emits network stats.
Fixed formatting
Renamed container description types
matches with the full path of the container
some more renames
Spec consistency
minor fixes and gofmt
Adding --log_cadvisor_usage flag to log the resource usage of cAdvisor.

This helps during performance analysis.
Merge pull request #269 from vmarmol/self-monitor

Adding --log_cadvisor_usage flag to log the resource usage of cAdvisor.
Mounted partitions space usage metrics per container

This computes the space usage for mounted partitions. It takes in a list of mounted partitions from containerHints
and computes the device's disk usage(so each mount must be a separate partition). This is useful for users who
mount partitions on containers and store most of the container's persistent data on those partitions.
Correct custom cAdvisor instructions

Point the user that wants to build a custom cAdvisor container to the actual location of the build script/Dockerfile.
Merge pull request #272 from highlyunavailable/master

Correct custom cAdvisor instructions
code review fixes
Merge pull request #270 from ashahab-altiscale/raw-network-handler

Raw cgroup handler network support using external hints file