Implement BlockDeviceMappings for LaunchConfiguration

We should support the BlockDeviceMappings for
AWS::AutoScaling::LaunchConfiguration resource to be
compatible with AWSCloudFormation, thus we can take
BlockDeviceMappings for instances in AutoScalingGroup
and InstanceGroup.

Implements blueprint implement-launchconfiguration-bdm

Change-Id: I26b13b8e98190fa4bb4223b5eed9970648d7ee35
Merge "Implement BlockDeviceMappings for LaunchConfiguration"