Recipe difficulty rating

[horaklukas]

Add reting of recipe difficulty. Invent symbol for this type of rating.

[horaklukas]

Possible solutions to use:

• https://github.com/dreyescat/react-rating
• https://github.com/Rudolph-Miller/react-bootstrap-star-rating
• https://github.com/NdYAG/react-rater
• https://github.com/senthilporunan/react-jrate
• https://github.com/ikr/react-star-rating-input