Redundant bool return in Validation functions

[nickajacks1]

The validation functions return both a bool and error(s).
It leads to simpler code to simply ignore the returned bool and check for len(errs) > 0 or err != nil
I suggest dropping the returned bool for the next breaking change unless there's some other purpose for it that I've missed

[daveshanley]

Good idea, it does seem redundant as an API design.