Remove locks from cluster read operations
Fixes for changes to samalba/dockerclient api
Set option to retrieve timestamps when getting logs back to false to retain default behaviour
ListContainers API now includes filter parameter that we don't need for the moment
Since 1.13/1.14 the image:tag format for image names is supported
Merge pull request #78 from tombee/remove-read-operation-locks

Issue #75: Remove locks from cluster read operations
Merge pull request #79 from tombee/upstream-fixes

Fixes for upstream changes to samalba/dockerclient api
return empty container list instead of error when cannot communicate with an engine