  The paper establishes the result that solutions of the type described in the
title of the article are only those that have been already presented in the
literature. The procedure adopted in the paper is somewhat novel - while the
usual practice is to display an exact solution and then to examine whether it
is singularity free, the present paper discovers the conditions which a
singularity free solution of the desired type must satistfy. There is no
attempt to obtain exact solutions. Simply, the conditions that were ad-hoc
introduced in the deduction of singularity free solutions are here shown to
follow from the requirement of non-singularity.
