GitLab

A few change to prepare for batch inference:

* Modify the return type of batch non max suppression to be tuple of tensors
  so it can be reused for both stages of faster rcnn without any confusion
  in the semantics implied the the keys used to represent the tensors.
* Allow dynamic number of anchors (boxes) in addition to dynamic batch size.
* Remove a redundant dynamic batch size test.

* Change dictionnaries iteritems() to items()

For details see our paper:
"Speed/accuracy trade-offs for modern convolutional object detectors."
Huang J, Rathod V, Sun C, Zhu M, Korattikara A, Fathi A, Fischer I,
Wojna Z, Song Y, Guadarrama S, Murphy K, CVPR 2017
https://arxiv.org/abs/1611.10012