fix(controller+client): utf-8 encode only string types
chore(utils): move encode to api/utils module
tests(controller): add api test for integer serialization/deserialization
fix(client): fix syntax error in config:list
fix(client): also encode keys which could be int
Merge pull request #1871 from gabrtv/fix-config-ints

Fix integer handling when encoding configuration
ref(builder): use ubuntu:14.04 as Dockerfile base image
ref(cache): use ubuntu:14.04 as Dockerfile base image
ref(controller): use ubuntu:14.04 as Dockerfile base image
ref(database): use ubuntu:14.04 as Dockerfile base image
ref(database): update postgres user uid/gid in confd templates
ref(logger): use ubuntu:14.04 as Dockerfile base image
ref(registry): use ubuntu:14.04 as Dockerfile base image
ref(router): use ubuntu:14.04 as Dockerfile base image
ref(tests): use ubuntu:14.04 as Dockerfile base image
chore(pip): update pip installs to 1.5.6