Myanmar-specific changes should get their own dedicated branch

[karpawich]

As of now, PR #325 for CrowdTangle Integration would merge in changes to Aggie that are specific to the Myanmar election. These changes introduce limitations to Aggie that make it easier to use in the case of Myanmar, but compromise its general-purpose quality.

I propose that we move all of our past, present, and future Myanmar-specific changes to their own dedicated branch (myanmar-2020, for example) so that the main branch can stay as the core of Aggie and can be available for other possible implementations in the future.