Tailing will only be stopped after LogWatch is terminated

It was the assumption so far that terminating tailing when there are no followers will be beneficial. However, to properly implement this, one needs to wait for the tailing thread to be terminated, before returning from the ```stopFollowing()``` method. And that can take quite some time, depending on the tailing refresh cycle - a time the calling code will not want to spend.

Therefore, this pull request changes the behavior. LogWatch will start tailing immediately after it is started, and  will only stop when it is terminated. LogWatch will be started automatically unless you explicitly disable that using ```doNotStart()```.