Use collection's get method inside ImageCollection's list method
Use collection's get method inside ImageCollection's list method

Signed-off-by: Adrian Liaw <32dfd1b028cebf606dbd90003bf6280c122b4fe4@gmail.com>

vpetersson/docker-py,funkyfuture/docker-py,vdemeester/docker-py,docker/docker-py,vpetersson/docker-py,vdemeester/docker-py,youhong316/docker-py,youhong316/docker-py,funkyfuture/docker-py,docker/docker-py