Ability to specify Host Devices during container start

[dims]

The command line and daemon started supporting --device
parameter during docker start a while ago in the following commit:
moby/moby@e855c4b

Since the command line looks like this,
--device=[] Add a host device to the container (e.g. --device=/dev/sdc:/dev/xvdc)
This patch allows a list of strings to be passed into the start() method
and we parse out the 3 components just like in the above mentioned commit

[shin-]

Thanks! _parse_devices should be placed in the utils module instead. =)

[dims]

Please see new pull request. my github-fu is broken, so ended up creating a fresh branch/PR.

#373