[REVIEWS] Improved usability, fixed pagination for authorized user

[annstriganova]

1. Task's name:

[IL-286] Post a review and rating

2. Developer's full name:

Anna Striganova

3. Changes:

• 0 is a default value for rating map
• renamed reviewCount -> reviewsCount
• fields of rating map are prefixed with star
• round of average value
• renamed POST /api/v1/products/{productId}/reviews -> /api/v1/products/{productId}/review
• implemented hack in JwtAuthenticationFilter that allows to exclude a review that was created by the authorized user