Fix typo in cache backend variable name
Move the schema hash generation methods to the cache key generation module
Add a test to ensure new cached associations expire existing IDC cache entries
Fix premature commit and merge where I was missing a line, sorry!!
Merge pull request #60 from RobWu/pg

PG quote issue fix
Quote the ID column in secondary index fetches so that postgres and assert_queries are happy.
Log deletes with both hits and misses in the cache proxy
Prevent inifinite loop for symmetric associations 

Fix for #62.

Test are running fine locally, but I am not sure about the general consequences of this change.