Remove System.Runtime.Numerics dependency from NodaTime.Testing. This looks like it's okay now.
Remove System.Runtime.Numerics dependency from NodaTime.Testing.
This looks like it's okay now.

Closes #510.

malcolmr/nodatime,jskeet/nodatime,BenJenkinson/nodatime,nodatime/nodatime,malcolmr/nodatime,BenJenkinson/nodatime,jskeet/nodatime,malcolmr/nodatime,nodatime/nodatime,malcolmr/nodatime