add default swiftformat settings (#23)

motivation: consistent formatting 

changes: add default formatting for `swiftformat`

Author: tomerd

.swiftformat

@@ -0,0 +1,10 @@
+# file options
+
+# format options
+
+--self insert 
+--patternlet inline 
+--stripunusedargs unnamed-only 
+--comments ignore
+
+# rules