Support GraphQL Schema Descriptions

[aklish]

Expected Behavior

Swagger (JSON-API) allows attributes and relationships to have user defined descriptions added to the documentation through the ApiModelProperty annotation.

GraphQL should support a similar mechanism.

Current Behavior

The description for attributes is left blank.

Possible Solution

Create a new Elide annotation that adds descriptions (and other attributes in ApiModelProperty) for both JSON-API and GraphQL fields.