DEV: Refactoring MS for BIT integration

[mtreacy002]

Is your feature request related to a problem? Please describe.
To achieve the target of 2 REST APIs (MS and BIT APIs) with one database (bit_schema database), MS schema needs to be refactored to accommodate BIT.

Describe the solution you'd like

• Refactor one of the UserModel field from organization to current_organization to remove ambiguity with Organization table reference used in BridgeInTech schema.
• Refactor the use of Float to Numeric with precision "16,6" so to avoid precision mismatch from data store/retrieve from db.
• modify .travis.yml to employ postgresql as db for testing on travis build
• add pytest-cov dependency in requirements.txt

Describe alternatives you've considered
NA

Additional context
This is a cross-project issue between MS and BIT where improvement will be made gradually throughout GSoC 2020 period.

[mtreacy002]

@anitab-org/mentorship-android-maintainers and @anitab-org/coding-team , this issue is a cross-project issue to prepare for BIT - MS integration.
Can you please add BIT label to this issue and assign it to me. I'll push a PR for this issue.

[mtreacy002]

Thanks @vj-codes 👍