refactor config variables in middlewares

optimized load of the config files in proxyquery and objectquery
now both of them will load some vars from corresponding server config (proxy-server or object-server)
it should avoid duplicating vars for both middleware section and server section
move retcode_map to module level constant
Merge pull request #58 from pkit/minor_fixes

refactor config variables in middlewares
now you can run zerovm on container server

added a new feature that allows you to specify Swift container database as one of the input files for the instance
proxy middleware support for container jobs

added support for querying container db files