Ignore is missing from LoadBIDSModelInputSpec

[adelavega]

Looks like in #187 additionnal arguments to LoadBIDSModelInputSpec were dropped in favor of only the database_path.

That's fine, but the problem is now arguments such as ignore have no where to go, and that section did not get updated:

   load_entry_point('neuroscout-cli', 'console_scripts', 'neuroscout')()
  File "/src/neuroscout/neuroscout_cli/cli.py", line 61, in main
    command(deepcopy(args)).run()
  File "/src/neuroscout/neuroscout_cli/commands/run.py", line 57, in run
    retcode = run_fitlins(fitlins_args)
  File "/opt/miniconda-latest/envs/neuro/lib/python3.6/site-packages/fitlins/cli/run.py", line 236, in run_fitlins
    smoothing=opts.smoothing, drop_missing=opts.drop_missing,
  File "/opt/miniconda-latest/envs/neuro/lib/python3.6/site-packages/fitlins/workflows/base.py", line 43, in init_fitlins_wf
    loader.inputs.ignore = ignore
traits.trait_errors.TraitError: Cannot set the undefined 'ignore' attribute of a 'LoadBIDSModelInputSpec' object.