Devices should be separated by colon separated string

Totally bad test :( (written by me). The documentation and
code should match now. Many thanks to pranavs18 for spotting
the error and proposing the fix.
Run Travis tests on Docker

Signed-off-by: Ben Firshman <ben@firshman.co.uk>
Merge pull request #430 from bfirsh/travis-docker

Run Travis tests on Docker
Merge pull request #429 from dims/master

Devices should be separated by colon separated string
* create_container now supports a host_config param
* Deprecation warnings added in Client.start
Added create_host_config helper in docker.utils
Updated mock API version
Updated unit tests
* Warnings will now raise exceptions in unit tests
* Updated several tests to use host_config
Prevent start_config from overriding host_config in create if no param is specified
Fixed VolumesFrom bug
Updated integration tests to use new host_config param
assertEquals -> assertEqual
Fixed start_container tests
Un-deprecated hostconfig in start
Re-added start with hostconfig tests
Re-added integration tests with hostconfig in start
Updated documentation with HostConfig information