logview: use dateutil for date parsing

Signed-off-by: Francois Andrieu <naolwen@gmail.com>

scripts/logview

@@ -1,20 +1,24 @@
 #!/usr/bin/python3
 import sys
 import json
-import time
 from optparse import OptionParser
-import subprocess
 import os
 import glob
+from datetime import date, timedelta
+import dateutil.parser as dateparser
+
+logpath = '/var/log/ansible'
+search_terms = ['CHANGED', 'FAILED']
+date_terms = {
+  "today": date.today,
+  "yesterday": lambda: date.today() - timedelta(1),
+}
 
-logpath='/var/log/ansible'
-search_terms=['CHANGED','FAILED']
 
 def date_cheat(datestr):
-    dc = subprocess.Popen(['date', '-d', datestr, '+%Y/%m/%d'], stdout=subprocess.PIPE, stderr=subprocess.PIPE).communicate()[0]
-    dc = dc.strip().decode()
-    return dc
-    
+    dc = date_terms.get(datestr, lambda: dateparser.parse(datestr))
+    return dc().strftime("%Y/%m/%d")
+
 
 def parse_args(args):
     usage = """