Adds more tolerance to QGIS mapserver for not fully OGC compliant WxS clients

At the moment QGIS mapserver is relatively strict in interpreting the REQUEST parameter. With this pull QGIS mapserver also accepts non compliant requests not using CamelCase e.g. REQUEST=getcapabilities. This pull does not brake the servers OGC compliance but makes it more tolerant for non-compliant clients. Even the OGC reference implementation (based on deegree ?) is relatively tolerant at this point.