Don't run the application in test environment

Summary:
Currently, the application was always initialized, and
only for the web server, a check the app wasn't imported
was done.

In an unit testing context, we don't always want to initialize
the application, for example it's not useful to test helper methods.

Yet, each time the app was imported, the check_config method was called,
and so software exited with error code 1 if environment wasn't correctly
configured, a requirement for the microservice, but not for the test suite.

Test Plan:

• Run the app, ensure server is spawned
• Import the app in another Python source code, ensure nothing is executed

Reviewers: dereckson

Reviewed By: dereckson

Differential Revision: https://devcentral.nasqueron.org/D1006