Initial setup of todo app.
add java 1.7 support
introduced jackson 2 for json handling;
implemented Mongo access.
fixed ObjectId type field JSON serialization issue.
implemented delete and update
implemented saveOne and patch (include mark done/undone).
Made the app works in heroku+MongoHQ environment.
Merge branch 'master' of heroku.com:rest-todo

Conflicts:
	src/main/java/org/example/todo/ToDoResource.java
	src/test/org/example/todo/ToDoResourceTest.java