Fix parallel version

Modifications:
Particle -> particles.Particle or particles.ParticleFull
ChargeConservingAreaWeighting -> ChargeConservingCIC
InterpolatorAlgorithm -> CloudInCell
YeeSolver -> SimpleSolver
remove obsolete comment about YeeSolver
Merge pull request #62 from aipp/fixparallelversion

Fixed the parallel version by the following modifications:
Particle -> particles.Particle or particles.ParticleFull
ChargeConservingAreaWeighting -> ChargeConservingCIC
InterpolatorAlgorithm -> CloudInCell
YeeSolver -> SimpleSolver