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
better detection of container query

currently the only channels that can be usable for running zerovm on container db are `stdin` and `input`
Merge pull request #59 from pkit/feature_container

support for running jobs over container sqlite3 database file
major bugfix patch for 404 errors

a lot of 404 was not handled correctly due to badly designed support for write-only objects
it lead to 5xx instead of 404 or 400 in quite a few places
needed to redesign the whole thing and check for 404 much earlier than before

wrote some regression tests
hope that all corner cases are covered now

Side note:
This patch uses `x-zerovm-access` header internally. And its value can be `GET` or `PUT`. Usually adepts of RestFul will ask "Why not use HTTP GET and HTTP PUT instead?" my answer would be: "Think."
Merge pull request #61 from pkit/bug_fix

major bugfix patch for 404 errors