update the LBNode fetching code to:
- have retries
- use the correct signature for request_func
  - pass the ServiceType
  - use the json_response=False argument when json is not desired
Merge branch 'pure-server-info-2' into lb-fetch-request-func-fixes
get rid of prints
Merge branch 'pure-server-info-2' into lb-fetch-request-func-fixes

Conflicts:
	otter/test/test_convergence.py
Merge pull request #790 from rackerlabs/lb-fetch-request-func-fixes

LB fetch request_func fixes

This does a couple things at once, but they're very minor:

- First, request_func by default returns JSON-parsed objects. This branch updates it to pass json_request=False when a non-JSON result is desired.
- Second, request_func changed to require a ServiceType parameter to indicate which service to talk to. This branch passes ServiceType.CLOUD_LOAD_BALANCER.
- Third, retries for all HTTP requests are added with a policy of 5 max retries and exponential backoff starting at 2 seconds.