2.4.4

Fix #14

Fix demos in README.md

• Fixed demos in README.md.

Implement new and fix existing properties

• Fixed work of hostLoading property of <graphql-query> web component.
• Implemented new errorPolicy property of <graphql-query> web component.
• Implemented new networkStatus property of <graphql-query> web component.
• Implemented new stale property of <graphql-query> web component.
• Removed the code of lastError property and custom error event (_handleError private method) from <graphql-mutation> web component, because they inherited from <graphql-query> web component.
• Updated descriptions of some properties.
• Improved the full demo (added "Refresh" button to "Query (search by content)" snippet).

Implement file uploads via GraphQL

• Implemented support of file uploads via GraphQL.
• Added file uploads demo.
• Bit refactored the source code.
• Updated docs.