Update UncertainFlorisModel to work with new Parallel framework

[paulf81]

Update UncertainFlorisModel to work with new Parallel framework

Note this PR replaces the outdated PR here: https://github.com/misi9170/floris/pull/1

The rework of the ParallelFlorisModel in #982 enabled an improved working of UncertainFlorisModel and ParallelFlorisModel. Previously ParallelFlorisModel would accept an UncertainFlorisModel and had special case handling to work with it. It has been discovered this code was not actually working the final result reflected a nominal result excluding the uncertain parameters. With the refactor it's more direct to simply have the UncertainFlorisModel accept aParallelFlorisModel (since the new version maintains a matched API to FlorisModel). This PR makes minor changes to the arguments and docstring of UncertainFlorisModel and specifically:

• Enables UncertainFlorisModel to be intialized by either a configuration like would be passed to a FlorisModel, or a FlorisModel itself, or a ParallelFlorisModel
• Adds a raise error to the prior version ParallelFlorisModel if an UncertainFlorisModel is passed in since this functionality doesn't work and won't be repaired.
• Adds a new example demonstrating the usage of ParallelFlorisModel and UncertainFlorisModel