some minor fixes

i.e., removing redundant namespace open- and closings due to the fact
that the property system now resides in the 'Ewoms' namspace instead
of in 'Opm', and making the headercheck work for all headers.

examples/problems/fingerproblem.hh

@@ -49,9 +49,7 @@
 namespace Ewoms {
 template <class TypeTag>
 class FingerProblem;
-}
 
-namespace Ewoms {
 namespace Properties {
 NEW_TYPE_TAG(FingerBaseProblem, INHERITS_FROM(FingerGridManager));
 
@@ -123,9 +121,8 @@ SET_SCALAR_PROP(FingerBaseProblem, EndTime, 215);
 
 // The default for the initial time step size of the simulation
 SET_SCALAR_PROP(FingerBaseProblem, InitialTimeStepSize, 10);
-}} // namespace Ewoms, Properties
+} // namespace Properties
 
-namespace Ewoms {
 /*!
  * \ingroup TestProblems
  *