Update asciidoc/04-data_exchange.adoc,...
Update asciidoc/04-data_exchange.adoc, files/samples-contrib/GuestRequests-OTA_ResRetrieveRS-request-with-emojis.xml, files/samples-contrib/RatePlans-OTA_HotelRatePlanNotifRQ-offer-with-emojis.xml files
Closes #26 (closed)