SMC ABC doesn't stop when max_rounds == 1

[BryanRumsey]

Proposed fixes

• RelativeEpsilonSelector constructor should raise an error if max_rounds == 0 and the doc string should indicate the required value.
• relative_epsilon_selector.py line 55: should return self.max_rounds == 1 for the has_more return value.
• smc_abc.py line 182: round should have an initial value of 2.
• relative_epsilon_selector.py line 81: should return self.max_rounds and round >= self.max_rounds for the terminate return value.