Make it possible to use a local "scrivito_resourcebrowser" gem


Since there are potentially many further gems one
would want to use from the local repos, the CLI
options for enabling / disabling the single repos
will get overwhelming, so they are completely
removed.
Simplified configuration of the local repos

No more explicit enabling / disabling of the
local repos. If there is a path to the local gem,
then it will be used as a local repo.
Bump version 0.4.0