snglbursttable.py: add template id attributes to GSTLALSnglBurst class.

- lalsuite's burca now imposes (or will when the merge request is accepted) exact-match coincidence as defined by .template_id.  this patch provideds backwards compatibility for string search

gstlal-burst/python/snglbursttable.py

@@ -10,3 +10,7 @@ class GSTLALSnglBurst(_snglbursttable.GSTLALSnglBurst):
 
 	start = lsctables.gpsproperty("start_time", "start_time_ns")
 	peak = lsctables.gpsproperty("peak_time", "peak_time_ns")
+
+	@property
+	def template_id(self):
+		return None