EXHIBIT 2

JOINT FILING AGREEMENT

The undersigned hereby agree to the joint filing of the Amendment No. 1 to the Schedule 13D to which this Agreement is attached.

Dated:  December 11, 2013
	DISCOVERY GROUP I, LLC,
	for itself and as general partner of
	DISCOVERY EQUITY PARTNERS, L.P.
	By	Michael R. Murphy*
		Michael R. Murphy
		Managing Member
	Daniel J. Donoghue*
	Daniel J. Donoghue
	Michael R. Murphy*
	Michael R. Murphy
	*By:	/s/ Mark Buckley
		Mark Buckley
		Attorney-in-Fact for Daniel J. Donoghue
		Attorney-in-Fact for Michael R. Murphy