Timelaps video is not complete when Webcam not response for a while

[midopple]

Sometimes my Webcam lost the connection, after reconnect the USB the Webcam works normal.

The Issue is that the picturecounter (self._imageNumber) count up without geting a picture from the Webcam. After reseting the Webcam, octoprint get pictures but the file numbering für AVCONV is broken like
tmp_00000.jpg, tmp_00001.jpg, tmp_00002.jpg, tmp_00003.jpg, tmp_00008.jpg,tmp_00009.jpg

I add a check in timelapse.py

def _captureWorker(self, filename):
eventManager().fire(Events.CAPTURE_START, {"file": filename});
try:
urllib.urlretrieve(self._snapshotUrl, filename)
except:
self._imageNumber -= 1
self._logger.debug("Image %s captured from %s" % (filename, self._snapshotUrl))
eventManager().fire(Events.CAPTURE_DONE, {"file": filename});

My Branch: devel, Commit: cec2bdb

[foosel]

Implemented in devel, good idea, thanks!