This adds new query arguments to the taskList hub xmlrpc endpoint, and then
makes use of those arguments in koji-web. A new optional configuration value
is added for koji-web: `HiddenUser`, which can be used to specify which user
account should be hidden. This could be useful for deployments that have a
continuous-integration account, the spam from which makes the frontpage
difficult to read.
Unit test cases are also added for some functions of the hub taskList endpoint.
Signed-off-by: Ralph Bean <rbean@redhat.com>
