Added conistent support for showing alerts on column widgets. The column controller now has a 'show_alert' which displays an laert badge above the search box. There are various types supported (same as Bootstrap). They all come with a close button, but the lower alerts close automatically after some time. I also updated the 'add_tool' function to simplify addition of tools. This function takes care of the wrapping 'form' and the setting up of hte callback handlers. See 'source_edit_global.js' on how that now looks like.
The return values from 'on_request' didn't account for the error cases
Firfox adds utf encoding information to the content-type. This change accoutns for that
Treating 'new' actions differently from all the others. This one will create a new widget of the requested type.