a variety of fixes, changes and adds

* Add:  global: link logo to main page (rcork)
* Change: index.php: current activity stream and codec details now
better mimic the terminology PMS and Plex/Web use (thanks rcork)
* Fix:  history.php: divide by zero errors (thanks rcork)
* Fix:  info.php: poster image sizing issue with safari on mac (thanks
rcork)
* Add:  global: default poster image for results that do not have an
associated poster image
* Fix:  index.php/user.php: recently added/recently watched poster
images would not appear if user moved or deleted item from PMS database
* Add:  config.php: Plex Media Server http/https support including
independant port numbers
* Add:  index.php: current activity now supports "clips" from your
myPlex queue