skeletal plugin
implemented GO_Marketo_API class and its get_auth_token() function
implemented the get_lead_by_id() and get_leads() functions, and associated unit tests
implemented GO_Marketo_API::update_lead() and related unit tests
removed some extra spaces
implemented the go_syncuser_user() action
implemented sync_user() function and get_sync_fields() function to retrieve lead data to be sync'ed to Marketo
more error-checking. (apparently Marketo's docs are not in sync with their actual API implementation...)
activate plugins needed by our config file in the PHPUnit environment
fixed the description
removed a commented out line
implemented GO_Marketo_API::add_lead_to_list() function and associated tests

add lead to the list defined in our config after update or creation
fixed a comment
made the test lead's email a class member var
implemented the admin dash sync button
some OCD spaces for @methnen and fixed a comment
fixed a mispelled class name
a little more validation
support the "overwrite" sync field configuration. when it's set to FALSE we will not overwrite a field if it already has content. otherwise we will overwrite. by default we overwrite all fields.

see https://github.com/GigaOM/legacy-pro/issues/3858
activate go-subscriptions in the unit test environment since we now call it from our config file