Clean up logging from glance_http.py

Currently the logging in the glance_http module is overly
verbose and doesn't add any extra useful information. This
commit condenses the logging and makes it analogous to the
logging in rest_client.py

Fixes bug 1089765

Change-Id: Ifa7038de27d979a60ff36b6e32b2cbe85541c231
Add negative test for get server in test_servers_negative.py.

This adds test for getting invalid server instance details
Fixes bug 1130519

Change-Id: I5df981700c549b0db04c06d823547f6fbb15f610
Merge "Add negative test for get server in test_servers_negative.py."