WMS_Null and empty error due to missing wms_service.properties in etc directory

[Bang Pham Huu]

With the current build with cmake, the file wms_service.properties does not exist in this install directory (etc/), then when deployed Petascope and initialize WMS, it just log and without throw exception then it runs normally.

However, when request WMS GetCapabilities, it will return a blank page due to it is NULL when initialising steps and see the log will notice it returns a NULL value.

This problem need to fix:
+ Check the file wms_service.properties can be installed to etc/
+ Change in PetascopeInterface with throw exception.

[Bang Pham Huu]

patch was accepted, close ticket.