get_info - removes duplicate code (Take 3)

Consolidate the different ways in which info of account/container
is gathered, cached, used, updated, etc.

This refactoring increases code reuse and is a basis for later
addition of account ACLs.
Changing the get_info users is left for future.
This staged approach ensures the behaviour is unchanged.

Change-Id: I67b58030d3f9e3bc86bcd7ece0f1dc693c4e08c3
Fixes: Bug #1162199
Merge "get_info - removes duplicate code (Take 3)"