Arc distance julia

From @serge-sans-paille

"""
I gave it a try in 

https://github.com/serge-sans-paille/python-benchmarks 

using a small makefile infrastructure to run static compilers when 
needed (cython & pythran). 

It's completely linux-centric... 

I started with the allmighty julia fractal code, from the cython 
tutorial given by Kurt during Scipy. Yuancheng added the arc_distance 
code. 

I failed to get good performance with numba and encountered an error 
with parakeet, so feel free to PR to update the codes accordingly. 

The code is slightly less structured than what Andy suggested, I opted 
for Alex KISS proposal as the benchmark codes are quite simple too. 

Any proposal / update / criticism are welcome ! 
"""