Revert BOB_NOSE_FAST hack in favour of using environment variables supported by nosetests

Closes bob.nightlies#55

See merge request !83

[sphinx] Fixed doc test

See merge request !82

Added @attr(slow) for slow tests

See merge request !81

[sphinx] Skipped somedoctests. The tensorflow 1.14 deprecation warnings are messing up with some doc tests and it's tricky to switch them off. Therefore, I'm skipping some doc tests

[style] Fixed issues with style-transfer

Closes #82

See merge request !80

Estimators optimize loss

Closes #78

See merge request !76

Fix issue with VGG16 from slim. The slim models adds the hot-encoded in the architecture function

See merge request !78

Organizing name scopes

Fixed the reuse in some operations of the inception-v1

See merge request !77