Moved configuration loading to new function
Pep8 fixes
Preparing refactoring, created update_model_type

  * Environ will have new key, model, which can be used
    to avoid if/elif/else checks on tasks like run, prepare
    or compile.
Generic compile_model task
Simplifiying code and splitting monolithic tasks

  * Each model must know how to prepare its inputs and workdir.
    Until now there was one prepare tasks that created dirs for
    all models.
  * Defined __all__ in models, so we don't export more than needed.
    This keeps namespace cleaner, allowing fabric task detection
    to work the right way.
  * Simplified run_model, don't need to check environ['type']
    because environ['model'] is defined now.