Fix some deprecations and factor out a helper function (#387)

files/routes/users.py

@@ -5,6 +5,7 @@ import math
 from files.classes.views import ViewerRelationship
 from files.helpers.alerts import *
 from files.helpers.sanitize import *
+from files.helpers.strings import sql_ilike_clean
 from files.helpers.const import *
 from files.helpers.assetcache import assetcache_path
 from files.mail import *
@@ -736,7 +737,7 @@ def api_is_available(name):
 	if len(name)<3 or len(name)>25:
 		return {name:False}
 		
-	name2 = name.replace('\\', '').replace('_','\_').replace('%','')
+	name2 = sql_ilike_clean(name)
 
 	x= g.db.query(User).filter(
 		or_(