This commit adds the devtools as a zip file containing both chrome
and firefox versions of the extension in the release and also updates
the doc to install it easily.
This commit adds the code of the owl devtools extension.
This extension can be added on chrome or on firefox for
developpers to be able to inspect the contents of all owl
applications that are present on any web page, see all the
components, interract with them and their content to some
extend and perform a bit of profiling with their renders.