Add parameter to execute() to match signature


git-svn-id: https://repo.thevirtualbrain.org/svn/tvb/trunk/framework_tvb@4981 1c0e02f0-7929-43c0-8fb3-3293bf43b0d1
TVB-945
Use runtime() method from the simulator, instead of having a dummy simple implementation in SimulatorAdapter.

git-svn-id: https://repo.thevirtualbrain.org/svn/tvb/trunk/framework_tvb@4982 1c0e02f0-7929-43c0-8fb3-3293bf43b0d1