clean-up of unused file

tutorials/icoFoam/cavity/FoamFile

-/*--------------------------------*- C++ -*----------------------------------*\
-| =========                 |                                                 |
-| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
-|  \\    /   O peration     | Version:  1.5                                   |
-|   \\  /    A nd           | Web:      http://www.OpenFOAM.org               |
-|    \\/     M anipulation  |                                                 |
-\*---------------------------------------------------------------------------*/
-FoamFile
-{
-    version     2.0;
-    format      ascii;
-    class       volScalarField;
-    object      p;
-}