Pipe nargs

Objective
-------------

I want the following command to work:

```command
dpmanip -s show_runs --parameters A Nx Ny
```

Summary
------------
Change format of `pipes_dists` defined in `dataprocessor/pipes/__init__.py`.

Old style:

```python
pipe_dics["show_runs"] = {
    "func": show_runs,
    "args": [],
    "kwds": ["project", "show_format"],
    "desc": "output runs path",
}
```

New style:

```python
pipe_dics["show_runs"] = {
    "func": show_runs,
    "args": [],
    "kwds": [("project", {"help": "project name"}),
             ("show_format", {"help": "format"}),
             ("parameters", {
                 "nargs": "+",
                 "help": "parameters to be displayed"
             })],
    "desc": "output runs path",
}
```

Both styles are valid in this patch.
Old style is converted into New style in `pipes/__init__.py`.