Update moment to 2.19.3

[jwalgran]

Overview

Incorporates bug fixes.

Connects https://github.com/OpenTreeMap/otm-cloud/issues/432

Testing

Setup

• vagrant provision app to install the updated dependency.
• Create an instance via http://localhost:6060/create

Moment

• Add a tree and choose the "continue editing" option to move to the detail edit page
• Enter a "Date Planted" value and save the tree
• Advanced Search for a date planted range and verify that the tree is matched.
• Edit and safe the Date Planted and verify that the value is correct after a refresh.

[coveralls]

Coverage remained the same at 83.867% when pulling 8d42a6154d465c6b0e1cea64aead4a2f4801af9e on jcw/update-moment into ae7c5c86e2d461baea6e212716cf90e160666fb3 on develop.

[jwalgran]

Matt is not available. There are no actual code changes, and I ran through the manual tests without and problems so I feel we can rely on release QA as a substitute review.