Mosek expopt support via both ctypes and the command line

(closes #1)

I got it working in the existing framework! But it's only twice as fast as CVXopt on my old computer?!
This even though the profiler says that it's spending >90% of its time running their C code. Maybe if you run `test_driven_development/simple_gp_example.py` the profiler will say something different, or maybe:
  - your computer is incredibly quicker than mine, or
  - that simple aircraft example wasn't the example you anticipated a 30x speedup for, or
  - Windows is terrible, or
  - their matlab implementation is pulling some additional tricks (e.g., multithreading).

I decided not to include the (modified) MOSEK C files in the repository; on my computer they're stored in a 'build' folder along with some make scripts I wrote for convenience. @whoburg , how should we deal with this?