[Groups] questions + answers + frontPage

db/migrations/20190511004131_create_messages_answers.js

db/seeds/02_dummy_metagroups.js

db/seeds/09_dummy_questions_answers.js

src/graphql/models/groupModel.ts

src/graphql/models/messageModel.ts

src/graphql/object_resolvers/groups/groups.ts

src/graphql/object_resolvers/groups/simpleGroups.ts

test/resolvers/data/2_user.ts

test/resolvers/data/onplatal/groups.ts

test/resolvers/data/user/groups.ts