allow promtail path to be a glob match (#206)

* allow promtail target path to be a glob match

Promtail now expects __path__ to be a glob. All files that match
the glob expression will be tailed.  If new files are created that
match the glob, they will immediately be tailed.

* remove entry from positions file when file is deleted

* fix syncing the current positions to positions file

* handle file renames

When a file is renamed a "rename" and a "create" event are sent.
We need to treat the rename as a remove.  If the new filename matches
the path glob, then we will start tailing it when the "create" event
is reveived.

* lint