change month number to name when adding archive entry to search DB.

This change is so the refinements on the seach page shows the month names
instead of thier numbers. This is because most people tend to work with month
names and not numbers in this context.

src/search.lisp

@@ -37,7 +37,8 @@ Note: The JSON object to encoded as a string."
       ("relative-path"  . ,relative-path-value)
       ("thumbnail-path" . ,thumbnail-path-value)
       ("year"           . ,(local-time:timestamp-year created-at-value))
-      ("month"          . ,(local-time:timestamp-month created-at-value))
+      ("month"          . ,(utils:month-number-to-name
+                            (local-time:timestamp-month created-at-value)))
       ("day"            . ,(local-time:timestamp-day created-at-value))
       ("keywords"       . ,(cl-ppcre:split "," keywords-value))))))