Merge Ionization into Dev to see changes

The code is compiling but once I try to run it, I am receiving a SegFault without much other comment. 
That happens when I use CUDA 5.5 or 6.0. If I use 6.5 it tells me that it cannot find a CUDA capable device.
GetCharge must be refactured in the future before this branch goes to the dev. The right version should look like `getCharge(Particle)`  but before we can implement this we need a new feature to partial cache particle attributes.