Merge in prior score vars - excluded when only baseline SGPs produced

"SCALE_SCORE_PRIOR", "SCALE_SCORE_PRIOR_STANDARDIZED" excluded even
when ONLY baseline SGPs have been produced.  Merge these variables in
for ALL cases
Add ability to use unique school names for WA (future school assignments)
Merge branch 'master' of github.com:CenterForAssessment/SGP
Fix to school names
Update to WA SGP_Configuration for studentGrowthPlots
Merge pull request #674 from adamvi/master

Update combineSGP and studentGrowthPlot_Styles for WA