update interface to generate spec and create interface from spec

[satra]

sometime this year, we should be able to have an interface that creates an interface on the fly based on a specification (CWL, Boutiques, SEM).

myInterface = CreateInterfaceFromSpec(path=[local, url]) #should support CWL, Boutiques, SEM

and then myinterface can be used as normal:

myInterface(...).run()
mynode = Node(myInterface(...), ...)

so the interface class should also have something like:

interface.toCWL()
interface.toBoutiques() # some of this is already there
interface.toSEM()