Additional Pipeline helper methods for imports

[Jim McStanton]

Currently Pipelines can import resources from other pipelines, but there is some wiring that the user needs to do to merge (small, but its there).

It would be nice if Pipelines had two additional methods:

• merge_resources that would support merging in:
  -- An array of resources
  -- A hash of resources (name to resource)
  -- An entire pipeline object
• import_pipeline that would merge all the resources from another pipeline into the calling pipeline
  -- Note that, for consistency, load_component should probably be renamed import_component