"Eat" unexpected backend exceptions

Added 2 inline functions in persistence.hpp
So that the '>>' operator works correctly for std::Vector<KeyPoint> and
std::Vector<DMatch>

- Allows using non-default device names such as /dev/v4l/by-path/pci-0000:00:1d.0-usb-0:1.1:1.0-video-index0

CvVideoWriter_GStreamer assumes a JPEG encoded stream if the height of
the given frame size is 1.

Added a writeFormat() method to Algorithm which must be called by the
write() method of derived classes.

syntax of cmake "get_filename_component" changed after version 2.8.11

for cmake version < 2.8.11
  get_filename_component(<VAR> <FileName> PATH [CACHE])

for cmake version >= 2.8.11
  get_filename_component(<VAR> <FileName> DIRECTORY [CACHE])

Update OpenCVConfig.cmake

Update OpenCVConfig.cmake.in