Make tests aware of new plek behaviour
Avoid expanding the index input into an array

Save memory when indexing 10,000's of docs. The documents may be an
enumarator or other lazy-evaluated iterable object so we can make this
more efficient by just iterating.
Validate documents during posting

This is to speed things up when posting a large number of docs. We avoid
iterating over the whole collection in advance.
Merge pull request #6 from alphagov/iterate-when-indexing

Iterate when indexing