Allow sorting and embedding by default in domain delaration
remove problematic multiplicity check
Merge branch 'feature/allow_embedding_and_sorting_in_domain_declaration' of https://github.com/nextsociety/eve into nextsociety-feature/allow_embedding_and_sorting_in_domain_declaration

Conflicts:
	eve/flaskapp.py
	eve/methods/put.py
Make tests work with PR #147.
Default sorting for API endpoints.
Default sort only active if 'sorting' enabled.
Test default sorting.
renamed 'sort' > 'default_sort' for clarity.
Documentation for default sorting.
Christoph Witzany
Union of both default and client embedding.
Test default field embedding.
Documentation for 'embedded_fields'.
Docstring update for both embedded_fields and default_sort.
Merge branch 'nextsociety-feature/allow_embedding_and_sorting_in_domain_declaration' into develop

'embedded_fields': default Embedded Resource Serialization on a list of
selected document fields. Eventual embedding requests by the clients
will be processed along with default embedding. In order for default
embedding to work, the field must be defined as embeddable and embedding
must be active for the resource itself.

'default_sort': allows to set endpoint default sorting. Default sorting
will be overridden by a client request that happens to include a ?sort
argument within the query string.