upgrading java version to 1.8, bumping version numbers to 2.0.0
removing Callback interface, using Supplier instead
changing back parent pom version to 1.0.0.
renaming bindTransactionManager -> setTransactionManager
setting parent of tests to 1.0.0, setting tests version to 2.0.0
Merge pull request #4 from erosb/master

upgrading to java8, removing Callback interface