Now with better tests and synchronisation that is more complete

Added statistics support (graphql-java#11)

* Added statistics support

* added delegating stats collector

* Added error counts to stats

* Added noop version of collector

* Made it doubles and added toMap

* javadoc warning

* batch load count is now the number of objects loaded via the batch function and batch invoke count the number of invocations of the batch function

* readme updates

* Made Statistics a class

Removing graphql dependency from dataloader

Merge pull request graphql-java#5 from graphql-java/3-instrumentation…

…-dispatcher

3 instrumentation dispatcher

Merge pull request graphql-java#5 from graphql-java/3-instrumentation…

…-dispatcher

3 instrumentation dispatcher

Migrating to graphql-java as a home - now with bintray publishing and…

… uses their signing