render useraction in redirect url
include useraction parameter in CHANGES
add mamachanko to AUTHORS
Merge pull request #39 from mamachanko/render-useraction

render useraction in redirect url
Bumping version to 1.2.2.
improve doc string
add _get_call_params to PayPalInterface
harness PayPalInterface._call with tests
utilise _get_call_params as param provider
raise error for call with None configs