Add Content-Dispotion header

Author: manu

src/http/http_headers.ml

@@ -29,6 +29,7 @@ let accept_language = name "Accept-Language"
 let accept_ranges = name "Accept-Ranges"
 let cache_control = name "Cache-Control"
 let connection = name "Connection"
+let content_disposition = name "Content-Disposition"
 let content_encoding = name "Content-Encoding"
 let content_range = name "Content-Range"
 let content_length = name "Content-Length"

src/http/http_headers.mli

@@ -36,6 +36,7 @@ val accept_language : name
 val accept_ranges : name
 val cache_control : name
 val connection : name
+val content_disposition : name
 val content_encoding : name
 val content_length : name
 val content_type : name