406 error with server 2.7

[Ngo Thanh Long]

DHIS2 server (version 2.7) send back the 406 status code (not accepted) when mobile client connect. Further debug found that the server return data in type of XML instead of "application/vnd.org.dhis2.mobile+serialized".

Note that this error is suspected of Spring 3.1 effect and only occur when running a whole dhis.war server (if run only the dhis-web-api-mobile.war , there's no error at all).