Investigate limiting couchbase.log file size in cbcollect

The main goal of this is to investigate methods of limiting the filesize of couchbase.log and looking into any problematic tasks that might be producing too much information such as the "fragmentation information" like was found in: https://issues.couchbase.com/browse/CBSE-16729 

One approach might be to limit the output on a per-task basis so we can fine-tune how much we want to show or discard based on what the task is. Alternatively, there are probably methods that involve a "total cap" in which we just bail as soon as we reach a specific maximum. The problem with this second approach, however, is that we would likely lose a good chunk of the necessary information in the cbcollect since they are ran in no particular order and it's unlikely the problematic task is the last one. I think we would rather limit the output of some tasks versus possibly missing other vital bits of information collected in couchbase.log