Revert #736 with maml and maml_omiglot (#752)
Summary:
This PR is reverting https://github.com/pytorch/benchmark/pull/736 because we prematurely removed `maml` and `maml_omiglot` models without adding proper replacements.
These models will later be replaced with a higher quality implementation from fewshot (https://github.com/oscarknagg/few-shot)
Pull Request resolved: https://github.com/pytorch/benchmark/pull/752
Reviewed By: jansel
Differential Revision: D34217403
Pulled By: xuzhao9
fbshipit-source-id: ee6ae9a553f218a8a378b491e0ddcce0cca5e965