WebStyle: /info pages using webdoc infrastructure

• Adds new admin interface to manage the /info space allowing a user to see and modify the contents of that space

• Adds jQuery File Tree plugin

• Adds new action 'runinfomanager'

• If the URL requested has an extension, look for the file on disk and send it back to the user with the correct mime type

• Adds a dictionary of mappings that allow us to bind any /info url to a dynamic page e.g. /info/hello can be mapped to HelloWebInterface() This dictionary is overridable by placing additional mappings in webdoc_info_mappings.py

• Uses bibdocfile stream_file function to use xsendfile when available.

Co-authored-by: Alessio Deiana <alessio.deiana@cern.ch>
Tested-by: Samuele Kaplun <samuele.kaplun@cern.ch>