This 'custom view' means that the URL to view the node (as returned by
url_for_node(…)) cannot be loaded via XHR and embedded in the project
viewer, but should rather be used as the actual browser URL instead.
Currently only blogs use this.
These changes mostly revolve around the change in ObjectId constructor
when running on Python 3.6. Where on 2.7 the constructor would accept
12- and 24-byte strings, now only 12-byte bytes and 24-character strings
are accepted. Good thing, but required some changes in our code.
Other changes include hashing of strings, which isn't supported, so they
are converted to bytes first, and sometimes converted back afterwards.
