use std importer configuration keys; pass max bandwidth & concurrency for downloads.
remove unused import.
Add model test.
updated node unit tests.
Merge branch 'master' into nodes-bandwidth-concurrency
add bandwidth and concurrency options support to nodes extensions.
remove unused import
add --max-downloads, max-speed to nodes command user-guide.
better user-guide formatting.
980506 - Fix creation of pulp cert file to have permission 600
Merge pull request #548 from pulp/nodes-bandwidth-concurrency

Support passing max-bandwidth and max-concurrency options for node synchronization.
Merge pull request #559 from pulp/barnabycourt-980506

980506 - Fix creation of pulp cert file to have permission 600
Merge branch 'master' into nodes-permit-extra-distributors

Conflicts:
	nodes/child/pulp_node/handlers/model.py