integrate openset method into AITom

[xulabs]

write 10 - 20 slides and add to google drive, need to complete before Sep 15

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The following tasks are not urgent, can be performed after the AAAI deadline

add the code under following module
aitom/aitom/classify/deep/supervised/cnn/openset

use existing functions in AITom as much as possible

write a tutorial and add to
https://github.com/xulabs/aitom_doc/blob/master/tutorials/011_openset_learning.py

prepare page and figures to be added to
https://github.com/xulabs/projects/openset_learning/readme.md

[d12306]

add the code for openset method in aitom/aitom/classify/deep/supervised/cnn/openset,

ready to write the tutorial and the readme.md

[xulabs]

@d12306 please remember to also add tutorial and the readme.md into the folder