Migrated codec checkers for JSON and YAML.
Moved codec checkers into own file, changed them to accept string instead of []byte, and added tests.
Merge branch 'master' of https://github.com/juju/testing into codec-checkers
Merge pull request #39 from juju/codec-checkers

Migrated codec checkers for JSON and YAML.
Fix failing test.
Merge pull request #42 from frankban/fix-test-error

Fix failing test.
Include the JSON helpers from charm store.
Move http/json helpers to a separate package.
Merge pull request #43 from frankban/include-http-helpers

Include the JSON helpers from charm store.