Exclude KDSoapServerObjectInterface.cpp from moc

CMake seems to detect that KDSoapServerObjectInterface.cpp needs
to have moc run on it, it does not. Set SKIP_AUTOMOC property to
exclude from auto moc, thus removing the following warning:

KDSoapServerObjectInterface.h:0: Note: No relevant classes found.
No output generated.
Merge pull request #16 from cjh1/fix-moc-warning

Exclude KDSoapServerObjectInterface.cpp from moc