fix for #531  urn:ogc:def:storedQuery:OGC-WFS::GetFeatureById 

accidentally removed merge branch on github, here the pull request again:

Following URN Code is used for StoredQuery identifiers:
urn:ogc:def:storedQuery:OGC-WFS::GetFeatureById
Following one is expected by compliance tests and a confirmed CR:
urn:ogc:def:query:OGC-WFS::GetFeatureById