Fix SimulatorTest.test_simulator_surface

CortexScientific._set_vertex_mapping if throwing an error when used for conectivity with cortical areas

index 94 is out of bounds for axis 1 with size 76

File "/opt/tvb/hudson_home/workspace/TVB - Linux64/scientific_library/tvb/simulator/simulator.py", line 308, in configure
self.preconfigure()
File "/opt/tvb/hudson_home/workspace/TVB - Linux64/scientific_library/tvb/simulator/simulator.py", line 261, in preconfigure
self.surface.configure()
File "/opt/tvb/hudson_home/workspace/TVB - Linux64/scientific_library/tvb/datatypes/cortex_scientific.py", line 54, in configure
self.region_average = self.region_mapping
File "/opt/tvb/hudson_home/workspace/TVB - Linux64/scientific_library/tvb/datatypes/cortex_scientific.py", line 138, in _set_region_average
self.region_sum = spatial_mask
File "/opt/tvb/hudson_home/workspace/TVB - Linux64/scientific_library/tvb/datatypes/cortex_scientific.py", line 164, in _set_region_sum
self.vertex_mapping = spatial_mask
File "/opt/tvb/hudson_home/workspace/TVB - Linux64/scientific_library/tvb/datatypes/cortex_scientific.py", line 215, in _set_vertex_mapping
vertex_mapping[numpy.arange(number_of_nodes), spatial_mask] = 1

Line 197 (where variable number_of_areas is defined) for Connectivity 192 it gets 76 (as many cortical areas are in this connectivity), but later it is indexing in an array of this size with absolute indices (as if the full connectivity is referred).