Merge pull request #246 from peastman/master

Detect if user specifies an unknown property name
Merge pull request #247 from peastman/master

Fixed some incorrect parameters in SWM4-NDP water model
Created wrapper classes for AVX vectors
Created AVX implementation of CPU nonbonded force
Improved vectorization of CpuNonbondedForce
Automatically select whether to use the SSE or AVX version of CpuNonbondedForce
Fixed bug in detecting if AVX is supported
Merge pull request #251 from peastman/avx

CPU platform can use AVX when available