Bump dep on docker-py
setup: bump docker-py version to 0.1.5

This allows gantry to manage Docker versions greater than 0.5,
where a UNIX socket is preferred over an HTTP socket.
Prefer the default Docker URI for a particular version

This commit changes the default docker.Client connection to use the default for
the currently installed version. Sacrificing being able to specify the URI is
worth it to allow gantry to manage all Docker versions, whether they use an
http or unix domain socket.
command.py: remove default docker url import
command.py: cleanup use of docker url
version: bump to 0.0.10
New argument to define how many containers to start

This is a slight change to former behaviour, where we decouple the previous
number of containers from the number of containers we want to start. This
number is settable via the `-n` commandline argument.
Bump version to 0.0.11
Add log output to container startup
Bump version to 0.0.12
Fix typo
Merge branch 'print-docker-run-command' into bump-version-to-0.0.12
Read application config from the appserver not the application
Merge pull request #1 from houst0n/app-config

App config