create activatePatient function in DAO

iTrust/src/edu/ncsu/csc/itrust/dao/mysql/PatientDAO.java

@@ -190,6 +190,22 @@ public class PatientDAO {
 		}
 	}
 
+	public void activatePatient(long mid) throws DBException {
+		Connection conn = null;
+		PreparedStatement ps = null;
+		try {
+			conn = factory.getConnection();
+			ps = conn.prepareStatement("UPDATE users SET role=? WHERE MID=?");
+			ps.setString(1, "patient")
+			ps.setLong(2, mid);
+
+		} catch (SQLException e) {
+			throw new DBException(e);
+		} finally {
+			DBUtil.closeConnection(conn, ps);
+		}
+	}
+
 	/**
 	 * Updates a patient's information for the given MID
 	 *