updated readme, delete readme.next 

git ignore generated source folder 

Merge pull request graphql-java#286 from dminkovsky/master Updated README For v2.3.0

illegal global id should yield illegal argument exception 

update reame to point to newest release 2.1.0 

cleanup: reformat code and optimize imports 

Merge pull request graphql-java#44 from henrikgs/master Fix example for GraphQLUnionType

add source location and message to all validation errors 

working on build process