allow to include js files from directories other than /static/js

this is initially for /static/RichText/ckeditor.js, which we want to include
in the default JSFiles so the rich messagebox could be always available.
add $Type to %ARGS so we can specify the type of the textarea in the caller

by default, the type is controlled by the system config($MessageBoxRichText)
and user preferences. however, sometimes we want to explicitly set the type no
matter what system config or the user preference is.

this is initially for the IPs and Addresses textareas in RTIR's ScriptedAction
tool page(/RTIR/Tools/ScriptedAction.html), where rich texts are not useful at
all(actually harmful as the backend doesn't handle the rich format).
Merge branch '4.2/message-box-type' into 4.2-trunk