Warn about empty globbing of `include.files`

Fixes #345
Add `parse_infos` to options, use it for "parsed file" message

This adds a new parse_infos besides parse_warnings, and uses it for the
'Included extra file "%s" during parsing' info.

Fixes #272
Merge branch 'issue-345-warn-on-empty-include-glob'
Merge branch 'issue-272-info-instead-warn-for-parsed-files'

Conflicts:
	supervisor/options.py