gstlal_ifo_stat: add status Ready for Virgo

Virgo wants status "Ready" to be displayed in addition to "Observing" and "Down" (link to issue). Status "Ready" should be the 0th bit up.

gstlal-ugly/bin/gstlal_ifo_stat

@@ -164,8 +164,14 @@ class IFOStatusTracker(object):
 				# only check 0th bit
 				state = "Observing" if (bit & 0b1 == 0b1) else "Down"
 			elif self.ifo == "V1":
-				# for Virgo check 0th and 1st bit
-				state = "Observing" if (bit & 0b11 == 0b11) else "Down"
+				if (bit & 0b11 == 0b11):
+					# check 0th and 1st bit
+					state = "Observing"
+				elif (bit & 0b1 == 0b1):
+					# check 0th bit
+					state = "Ready"
+				else:
+					state = "Down"
 			else:
 				raise ValueError(f"Unsupported interferometer: {self.ifo}")