Merge pull request #261 from vmarmol/release

cAdvisor 0.4.1 release.
Adding filesystem usage information to MachineInfo.
Filesystem stats are now per container. As of now, fs stats are reported only for the
root cgroup.
To make cadvisor detect all the disks, the rootfs of host needs to mounted
inside cadvisor.
Adding a disk usage progress bar.
Merge pull request #258 from vishh/disk_usage

Adding global filesystem usage information
Adding filesystem stats to db storage drivers. Moved FsStats to info package.
Adding Subcontainers to cAdvisor client.

Also refactoring and improvements.
Merge pull request #264 from vishh/disk_usage

Adding filesystem stats to db storage drivers.
Merge pull request #265 from vmarmol/client

Adding Subcontainers to cAdvisor client.
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