[INTERNAL] I18N: for HANA XS, add languages 1Q/2Q also as URL parameter 

HANA XS Engine can't handle private extensions in BCP47 language tags.
Therefore, sending 1Q/2Q in the Accept-Language header doesn't work. 
As a workaround, HANA XS wants to receive these languages via the
sap-language parameter.

This is a hack and should be removed once all supported XS Engine
versions understand the full BCP47 standard for the Accept-Language
header.

Additionally fixed some whitespace and JSDoc issues.

Change-Id: I65c63f6384fc9c23d5bb05fb519ab09fb75e9012
Merge "[INTERNAL] I18N: for HANA XS, add languages 1Q/2Q also as URL parameter "