Fix federation documentation reference

The documentation for the federation extension referenced a class
that doesn't exist for the driver. Using the correct class name
will make it easier for deployers to configure federation.

bp identity-providers

Change-Id: I0f69d3465be78079a89e6d2c5e717aed04136a50
Fix docstrings in federation controller.

This fixes a couple of nits with the docstrings in the federation
controller.

bp identity-providers

Change-Id: I3db9478aaf02ac3ac5fb1e463baf014d7bb88975
Remove autoincrement from String column.

Passing autoincrement is not necessary because the column is a
String.

bp identity-providers

Change-Id: Ied5d8953464094d678fa934f78a7e11457ba73dc
Don't set default for a nullable column

The "description" column for identity providers is nullable, so
there's no need to set the default for the value.

bp identity-providers

Change-Id: Ib623214f029085845c26609b506f70ae91502cfc
Merge "Fix federation documentation reference"
Merge "Fix docstrings in federation controller."
Merge "Remove autoincrement from String column."
Merge "Don't set default for a nullable column"