Unified snake_case usage.

Use same snake_case in all places. Corrects problem where wrong method format is used when receiving response in some cases (e.g. SetCurrentAVUri (camel case) -> set_current_avuri (request) -> set_current_a_v_uri (response)).

Also increased version of used nokogiri to be able to use globals.convert_response_tags_to -globals of the nokogiri.