| EXHIBIT 2 |
JOINT FILING AGREEMENT
The undersigned hereby agree to the joint filing of the Amendment No. 4 to Schedule 13D to which this Agreement is attached.
Dated: July 22, 2015
| 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 |