fix: Fix RestApiResponse deserialization

[ruslan-malona]

JIRA Ticket

Subject Text

I tried to use RestApiResponse class as a response type for method in our SDK and faced an issue with deserialization:

com.fasterxml.jackson.databind.exc.InvalidDefinitionException: Cannot construct instance of `com.smartling.api.v2.response.RestApiResponse` (no Creators, like default constructor, exist): cannot deserialize from Object value (no delegate- or property-based Creator)

I'm adding a default constructor here and a setter to fix deserialization of this class

[ruslan-malona]

for some reason circle ci didn't run pipeline for this branch, creating new one: #60