Timers

• new dg::blas1::evaluate functions
• all Time steppers are now time dependent and have a nicer interface -> the above two features make the Method of Manufacture Solutions possible
• DG_DEVICE macro for easy functor generation for both cpu and gpu
• Multistep and Karniadakis now guarantee synchronous fields and potential computations
• updated all src, diag and geometries programs to jsoncpp c++11 branch
• updated all src projects to new time dependent steppers