v3.0 / Future: Proposal to rename some params to clarify SP vs. IdP

[johnnyshields]

The most difficult thing for me when learning RubySaml was "What is an IdP setting, and what is an SP setting." I would like to propose to change some param names to make this more explicit.

Current Name	Proposed New Name	Notes
name_identifier_format	sp_name_identifier_format (?)	Need to clarify whether this is SP or IdP
name_identifier_value	sp_name_identifier_value (?)	Need to clarify whether this is SP or IdP
name_identifier_value_requested	sp_name_identifier_value_requested (?)	Need to clarify whether this is SP or IdP
sessionindex	???
double_quote_xml_attribute_values	sp_metadata_double_quote_attribute_values
message_max_bytesize	sp_message_max_bytesize
passive	sp_authn_request_is_passive
protocol_binding	sp_authn_request_protocol_binding
force_authn	sp_authn_request_force_authn
attributes_index	sp_attributes_consuming_service_index
authn_context	???
authn_context_comparison	???
authn_context_decl_ref	???
check_idp_cert_expiration	idp_check_cert_expiry
check_sp_cert_expiration	sp_check_cert_expiry

Should also consider making settings.security to be regular parameters rather than a Hash (see #694)