Add initial step

The initial step is in charge of choosing what kind of analisys will be
performed in the workflow. For each of these analysis, a json file will be
added in the resources to help the CLIs.
Right now there are now json files, so Readme are added to make sure the
folder are taken into account by git.
Update workflow GUI from CLIs

The workflow was already updating the CLIs in slicer with its own
parameters. Now, the workflow GUI can update itself from the CLIs it uses
by overloading the method updateFromCLIParameters(). This method is called
by the workflow on the steps everytime the worflow module is shown. The
default implementation in WorkflowStep does nothing. So far, this only
applied to the RegisterStep.

Also, instead of using BrainsFit, the registration uses the cli
ExpertAutomatedRegistration.