Feature: Add support for default argument value of macros

[zackad]

Close GH-69

[zackad]

Missing quote when printing string value as default argument.

Expected output

+ {% macro hosted(
+     fontFamily,
+     filenameWithoutExt = false,
+     fontWeight = 400,
+     fontStyle = 'normal',
+     preload = false)
+ %}

Actual output

+ {% macro hosted(
+     fontFamily,
+     filenameWithoutExt = false,
+     fontWeight = 400,
+     fontStyle = normal,
+     preload = false)
+ %}