CMosek added variable bounds

Hey @iglesias I made changes in Mosek.cpp for adding bounds on variables. Unfortunately, I have to touch many files to make the arguments consistent. Could you review the little patch for me? 

I am not sure we want to add unit-test for Mosek related class. But I am pretty sure these changes make sense. I have tested them on my own computer. BTW, I think @Jiaolong will test this part of code in his GraphCut inference thoroughly. 
Hmm I am not sure why passing all these SGVectors by reference. @hushell, why?