Group and post recommendations UI

[smddzcy]

About

• Related Issues: #175 #184 #141

Now we display the group and post recommendations in the news feed. This PR also includes some bug fixes and minor improvements.

Closes #175

Changes

• Implement the post and group recommendations UI.
• Fix the voting feature.
  • Set the owner of the vote on the backend.
  • Split the serializer into two: VoteCreateSerializer and VoteSerializer.
• Use serializers in the recommendation endpoints instead of manually selecting which fields to return.
• Redirect the user to the news feed on login and signup instead of the groups page.

Visuals

Recommendations for user 1	Recommendations for user 2

Testing

• Go to the news feed page.
• You should see your recommended groups and posts, and you should be able to interact with them (cast votes, add comments etc.) without any problems.

[karacasoft]

'All checks have failed' :V

Add tests for voting feature and it'll be done.

[smddzcy]

@triforce930 I couldn't set up the Travis, you can help me on feature/travis branch if you want 😄 I won't add tests for the voting feature because it's not the concern of this PR; I just fixed that to test my feature. Please continue on another issue/PR if it has other problems or if you want tests/other things.

[karacasoft]

Ok then