Loosen import_exceptions to cover all of gettextutils

Now that we are starting to move over to multiple log domains we want to
import multiple items on the same line for gettextutils.

Change-Id: Icd88774a0f1087270234a6849bf96a93c0927534
Remove metadata's network-api dependence on the database

This makes the metadata server use instance.info_cache for getting
an instance's info cache instead of going direct to the network-api
(and thus, the database) for it. It also converts the network-api
implementation of get_fixed_ip_by_address() to use and return an
object. Since that translates to the same DB call in the end, none
of the network tests need to change.

Change-Id: Iab444b1669628604f7d96d9550eb684645c554cb
Closes-bug: #1306009
Merge "Loosen import_exceptions to cover all of gettextutils"