Inception Score

[gucifer]

Description:
First Implementation of Inception Score

Check list:

• New tests are added (if a new feature is added)
• New doc strings: description and/or example code are in RST format
• Documentation is updated (if required)

[vfdev-5]

Thanks for the PR @gucifer ! Few comments to address.

[gucifer]

@vfdev-5 everything else apart from Inception model argument is done. Can you check and review?
I will start working on a common Inception class meanwhile.

[sdesrozis]

I will do it asap

[vfdev-5]

Thanks @gucifer , @sdesrozis !