Removed obsolete calls, harmonized predefine response, added non admin user pages.

When access is denied, also provide when possible and wanted, the needed
permissions so that in the future, user will be able to ask for
permission easily.
Renamed previous user handlers as admin user handlers.
Added non admin user handler /user/{uid} .
Add new `send_...` response to `CMS_API.response_api`, and use them
instead of `create {...RESPONSE}.... ; execute`.
Fixed potential issue with storage mailer initialization if folder does
not exist.
Added utf_8_encoded helpers function on CMS_API interface.
Fixed a few unicode potential issues.
Removed a few obsolete calls.

src/theme/missing_theme/missing_cms_theme.e

@@ -47,7 +47,7 @@ feature -- Access
 	page_html (page: CMS_HTML_PAGE): STRING_8
 		do
 			to_implement ("Add a better response message, maybe using smarty template")
-			Result := "Service Unavailable"
+			Result := "Service Unavailable (missing theme!)"
 		end
 note
 	copyright: "2011-2017, Jocelyn Fiat, Javier Velilla, Eiffel Software and others"

src/theme/smarty_theme/smarty_cms_theme.e

@@ -40,7 +40,6 @@ feature -- Access
 	regions: ARRAY [STRING]
 		local
 			i: INTEGER
-			utf: UTF_CONVERTER
 			l_regions: like internal_regions
 		do
 			l_regions := internal_regions
@@ -51,7 +50,7 @@ feature -- Access
 					across
 						tb as ic
 					loop
-						l_regions.force (utf.utf_32_string_to_utf_8_string_8 (ic.key), i) -- NOTE: UTF-8 encoded !
+						l_regions.force (utf_8_encoded (ic.key), i) -- NOTE: UTF-8 encoded !
 						i := i + 1
 					end
 				else