Face-recognition

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* Added --show-distance to cli
* Fixed a bug where --tolerance was ignored in cli if testing a single image
* Added benchmark.py to examples

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* Added --tolerance to cli

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* The CLI can now take advantage of multiple CPUs. Just pass in the -cpus X parameter where X is the number of CPUs to use.
* Added face_distance.py example
* Improved CLI tests to actually test the CLI functionality
* Updated facerec_on_raspberry_pi.py to capture in rgb (not bgr) format.

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* Fixed a ValueError crash when using the CLI on Python 2.7

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* Raspberry Pi support.

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* Fixed: Face landmarks wasn't returning all chin points.