Remove all TODOs comments from code

[Ivan Kolodyazhny]

Go through every TODO in the code, and either turn it into a bug or remove it

Etherpad doc is here: https://etherpad.openstack.org/p/cinder-kilo-todos-cleanup

[Imran Hayder (hayderimran7)]

https://review.openstack.org/#/c/126993/
Though i removed all the TODOs comments and committed , change is abandoned since a reviewer added that too much subtle info there is in TODOs, removing all these comments wont add anything meaningful.
See comments in above review link.

Also, read the 'pylintrc' file in cinder repo, it clearly says 'TODOs are fine to be added as comments'

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/134574

[OpenStack Infra (hudson-openstack)]

Change abandoned by Roman Vasilets (<email address hidden>) on branch: master
Review: https://review.openstack.org/134574

[Sean McGinnis (sean-mcginnis)]

Only a small number of TODOs in the client code now, and most of them should probably stay as notes for things to think about in the future. I think these and any others will have to be handled on a case by case basis, so closing this bug as invalid as I don't think we want to do a blanket removal of all instances at this point.