[ipcamera] Fix null URL channels and fix multiple cameras use the same ffmpeg output folder.

[Skinah]

Fixes two issues:

1. Bug catches a number of users where the camera thing comes ONLINE and then they create and link items for the url channels. The channels stayed null until the binding was restarted, or a config of the thing was changed. This fix now updates the channels when it detects they link to an item to these channels. Making this change should reduce new user frustration and would be good to get this into the next stable build.
2. Issue 10661 reported by a user raises that if someone does not edit the default ffmpegOutput path, multiple cameras can then use the same folder and create issues. Fix works by using the UID to ensure the path is unique and can be set to a friendly name automatically with the UID when the thing is created.

Some refactoring was also done to reduce some newly added code analysis warnings.

Precompiled jar can be found here:
http://pcmus.com/openhab/IpCameraBinding/

Signed-off-by: Matthew Skinner [email protected]

[Skinah]

All suggested changes have been made.

[Skinah]

Thanks for suggestions, review and catching the typo. All changes have been made.

[fwolter]

LGTM