New Boutiques module to validate strings used as filenames

[prioux]

Many tools integrated with boutiques descriptors have inputs of type 'String' that are used to provide a output path or basename for whatever files the tool is going to create. These are also used as part of the templates in the 'output' sections to tell CBRAIN what is to be saved int he database.

For exmaple, in the "inputs" section:

        {
            "description": "The name of the folder to store outputs of XCPD processing.",
            "id": "output_dir",
            "name": "output_dir",
            "optional": false,
            "type": "String",
            "value-key": "[OUTPUT_DIR]",
            "default-value": "xcpd_output"
        }

and in the "output-files" section:

        {   
            "name": "XCPD Subject Output Directory",
            "id":  "xcpd_output_dir",
            "description": "Subject level output for XCP-D",
            "optional":  false,
            "path-template": "[OUTPUT_DIR]"
        }

The prevent problems, right from the start before launching a task, we should validate them a little bit and make sure they respect the rules that CBRAIN impose for userfiles. A new custom modules need to be implemented which would be provided with the IDs of "String" inputs to check against the CBRAIN userfile naming rules, e.g.

        "cbrain:integrator_modules": {
            "BoutiquesOutputNameValidator": [ "output_dir", "other_id", "other_id_2" ]
        }

[prioux]

The Ruby method to validate names is

   ok = Userfile.is_legal_filename?(name_to_check)