1102877 - updated get_youngest_child function to take into consideration parent image layers having multiple children
1103330 - updating various functions and unit tests to support docker images have multiple leaf layers and parents having multiple child layers
Merge pull request #21 from pulp/skarmark-1102877

1102877 - updated get_youngest_child function to take into consideration parent image layers having multiple children
resolving conflicts with master and added logic to avoid creating muliple DockerImage models in case of multiple children sharing a parent
Minor fix in a unit test
splitting a couple of unit tests into separate tests
Merge pull request #22 from pulp/skarmark-1103330

1103330 - updating various functions and unit tests to support docker images have multiple leaf layers and parents having multiple child layers
merging master and resolving conflict