ckanapi: docstrings!
start of schema_description docs
schema_description attributes
rename dataset_fields_by_ckan_id and resource_fields_by_ckan_id to dataset_field_iter and resource_field_iter
README: description of metadata schema field data
README: small fixes, add field 'type'
Merge pull request #96 from wardi/master

README: new schema_description description; renamed dataset_fields_by_ckan_id and resource_fields_by_ckan_id