Nullable objectid with null value stored as null.

Closes #341.
Fix typo in module name.
David Arnold
enumerate all the things
Merge pull request #1 from nicolaiarocci/develop

Update
correction in the `default` rule description
Merge branch 'da4089-develop' into develop
Merge pull request #345 from superdesk/develop

fix(links): make use of URL_PROTOCOL in document/resource link
UUID urls as regexes
Merge pull request #347 from girogiro/develop

correction of the 'default' schema rule description
Merge branch 'develop' of github.com:superdesk/eve into superdesk-develop
Improve RETURN_MEDIA_AS_BASE64_STRING docs
Magdas Adrian
Merge branch 'superdesk-develop' into develop
Explicit edit and delete HTTP methods. Addresses #350.
Fix crash with non-existing custom ID_FIELD.

A custom ID_FIELD would crash on GET requests to resource endpoints if
one or more documents were missing the ID_FIELD (probably because they
were created before the custom ID_FIELD was set). The crash would happen
while building the HATEOAS link to the document.

In general, documents like this are bogus since they miss the only field
which would allow them to be retrieved, edited and deleted. This 'fix'
avoids building the document link if the active ID_FIELD is missing for
the document, which in turn allows GET requests on the resource
endpoints to function properly.

An extreme alternative would probably be to skip documents like these as
they don't validate against the current API settings.

Closes #351.
Default values are now resolved before validation.

 Closes #353.
Allow readonly field with a default value to pass validation.

Addresses #353.
Allow versioning tests to pass with new default field.

Addresses #353.
PyMongo v2.7.1