Adding number of refreshes to metrics

This new metric was implemented by Ana Mativi <anaclara@rhrk.uni-kl.de> and
then removed by mistake in 14c4a041bd.

DRAMSys/traceAnalyzer/scripts/metrics.py

@@ -228,6 +228,14 @@ def number_of_accesses(connection):
     return result[0]
 
 
+@metric
+def number_of_refreshes(connection):
+    cursor = connection.cursor()
+    cursor.execute("SELECT COUNT(*) FROM Phases WHERE PhaseName = 'REFA'")
+    result = cursor.fetchone()
+    return result[0]
+
+
 @metric
 def bank_overlap_ratio(connection):
     # Calculates how many banks are open in parallel