apollo-compiler@1.0.0-beta.15

Features

• Serialize with initial indentation - SimonSapin, pull/848
  This helps use indentation in something that is partly but not entirely GraphQL syntax,
  such as the debugging representation of an Apollo Router query plan.
  Example: document.serialize().initial_indent_level(2).to_string()
• Add validation requiring composite types declare fields - tinnou, pull/847
  Object types, interfaces, enums, unions, and input objects must all have at least one
  member. This is now checked in schema validation.