Merge pull request #1 from gadventures/cache_options

Ability to configure the cache backends
Clear redis cache using key prefix only

Flushall would have emptied the entire cache which is
almost certainly what nobody wants
Add ability to get a fresh copy of the resource

New parameter `cached` added to `Query.get` which will
ignore the cache on fetch and update it with the latest
resource data.
Merge branch 'master' of github.com:gadventures/gapipy into cache_options