Improvements to logging stacktraces
Fixes in logging and peer management

  * Reduced logging levels used in peerclient
  * Added max limit on total number of peers we maintain (disconnected + connected + handshaking)
Fixes and improvements

  * Improved PieceManager:
    * Fixed possible deadlock between start/wait in PieceManager
    * Don't enqueue requests if PieceManager has been stopped
    * Added testcase for stop
  * Fixed thread leak: PieceManager worker threads were not being stopped when torrent was removed from PeerClient
  * When updating our peer list from the tracker, if we reach the max peer count we replace old disconnected peers
  * Updated tests to use new LogManager setup method
  * Fixed test_util to call arrayShuffleRange properly