Add tests

[xepozz]

Need to cover each functionality with test.

Unit:

• Tests for raw data => object transformation
  • Post
  • Comment
  • Reactions
  • Vote
• Tests for caching mechanism

Acceptance:

• Posts
  • Posts is loading
  • Single post is loading
  • Comments is loading
  • Likes/Dislikes is loading
• Filtering
  • Filters by tag is working
• Caching is working
• Auth token can be stored