Store xtas results as child documents on the parent document rather than as a property (issue #17)

The document type for children is a concatenation of type__task1__task2.
This is not very elegant and it will break if we have more complex pipes
or use parameters. Maybe a hash on the actual pipeline/header is a better
idea?

The child needs to have a proper mapping to specify parent, which is
currently checked before store_single.

I removed the get_all_results functions since it is never used and it caused troubles
if called before the first store_single
Add elastic version check to tests
Multiple indexes with the same document id can now be created.
	modified:   xtas/tasks/es.py
Get the tasknames on an index. Tests are there but not tested: nosetests doesn't work yet.
get all data per document, no test
Fetching documents per task and fetching results when querying a document.
Starting with returning the *full* document, including all task resutls
started on tests
Merge branch 'master' into hendrike-es-integration-merged

Conflicts:
	xtas/tasks/es.py
Adding todo for tomorrow.
	modified:   xtas/tasks/es.py
Wild querying of documents + returning the xtas results is now possible.
Can restrict by tasknames.
Added some tests.
Some prettification
Pep8
	modified:   xtas/tasks/es.py
pep8
	modified:   xtas/tests/test_es.py
Making tests pass.
	modified:   xtas/tasks/es.py
	modified:   xtas/tests/test_es.py
update tutorial for new way of storing stuff
Merge pull request #1 from NLeSC/pr72-with-tutorial

update tutorial for new way of storing stuff
Merge pull request #72 from mariahendrike/hendrike-es-integration-merged

New ES integration code