Update README to describe SCons installation.  - refs eggplantbren/DNest4#11
Update README to describe SCons installation.
 - refs eggplantbren/DNest4#11

eggplantbren/DNest4,eggplantbren/DNest4,eggplantbren/DNest4,eggplantbren/DNest4,eggplantbren/DNest4