This PR makes important project structure changes.
It also fixes the following issues:
Messed up "Logout Vsts"/"Switch Vsts Account" command names;
Create new app appearing in non-react project and attempting to work
* Implemented tests.
* Tslint
* Some refactoring.
* Added one more check.
* Added tests for several more methods.
* Renamed test suite.
* Added deletion of test files.