Sprinkle raw strings across the code base

tox / pytest is complaining about lots and lots of invalid escape
sequences in our code base. Sprinkle raw strings or backslash escapes
across the code base to fix most occurences of:

  DeprecationWarning: invalid escape sequence

There is still one warning that keeps repeating, though:

  source:264: DeprecationWarning: invalid escape sequence \d

Signed-off-by: Christian Heimes <cheimes@redhat.com>
Reviewed-By: Florence Blanc-Renaud <frenaud@redhat.com>

ipalib/aci.py

@@ -127,7 +127,7 @@ class ACI(object):
 
             if var == 'targetattr':
                 # Make a string of the form attr || attr || ... into a list
-                t = re.split('[^a-zA-Z0-9;\*]+', val)
+                t = re.split(r'[^a-zA-Z0-9;\*]+', val)
                 self.target[var] = {}
                 self.target[var]['operator'] = op
                 self.target[var]['expression'] = t