docker-test-1.0.0: Generalize mm/dd rules to accept spaces like '05 / 27', '05/ 27'

Summary:
The existing "mm/dd" rules only accepts format like "05/27"; However, in practice there might be extra spaces like "05 / 27", "05/ 27". The pull requests tweaks the regex to accept extra space.
Closes https://github.com/facebookincubator/duckling/pull/31

Reviewed By: niteria

Differential Revision: D5147118

Pulled By: patapizza

fbshipit-source-id: f6a5069