Test/118: AddFriends unit test

[arielbk]

Unit tests for the addFriend component and the addFriend Redux action creator.

Refactors some of the code for adding a friend.

Link to Issue:

• Fixes/Closes #118

Readiness:

• [x] Avoid duplicated logic
• [x] Unit test component functionalities
• [x] Use semantic HTML tags
• [x] Use semantic commits
• [x] Connect this Pull Request to an issue