Update Kaleidoscope Chapters 3, 4 and 5 to use OrcJIT

[mjsabby]

Since JIT is no longer available in LLVM 3.6, moving to MCJIT is essential as folks try to run the tutorial and find that it's mysteriously broken.

[mjsabby]

I suppose we can skip over MCJIT and move to OrcJIT now that it looks like C API support is around the horizon.