fix: decision service for group and multiple experiments.

[ozayr-zaviar]

Summary

• get_variation_for_feature code updated to fix group and multiple experiment issues.

Fixes:

• Currently only first experiment is picked through feature.experimentIds[0]. Which is fixed by using loop.
• Group experiments are evaluated first then individual experiments are evaluated instead of evaluating first occurring experiment in feature like in other SDKs which is fixed by removing condition for group experiments.

Test plan

• New test cases for group experiments should pass in FSC

Issues

• Need to fix test cases for get_variation_for_feature after current changes in Python.

[msohailhussain]

Remove the code in project_config.py where feature.groupId is set since it's no more of use after changing the logic.

[coveralls]

Coverage decreased (-0.04%) to 95.838% when pulling f0d9f60da5c3ea04c5981db3a159ef336cec51f2 on uzair/decision-service-for-group-fixes into 46651fa238a88a9ba8bf15ddcd69a83c7f645bf2 on master.