Set valid and message properties on token generation results
Set valid and message properties on token generation results

+ If token generated set valid to True and message to "Token Generated"
+ If token NOT generated set valid to False and message to request
return value

* OAuthSecurityHandler was always returning valid = True

adegwerth/ArcREST,BrunoCaimar/ArcREST,DShokes/ArcREST,Esri/ArcREST,pLeBlanc93/ArcREST