af_match_template feature

* cpu backend implementation added with the following metrics
      * SAD
      * ZSAD
      * LSAD
      * SSD
      * ZSSD
      * LSSD
* place holders for cuda and opencl backends added for now
* invalid argument unit tests added
* unit tests for matrix(image) and batch matrices(images) added
  for SAD, SSD metrics.
* unit tests data corresponding to this commit also updated