adding the php type cast mode, where string data that represents a valid double or integer is validated ok agains a schema definition of number or integer.

git-svn-id: https://jsonschemaphpv.svn.sourceforge.net/svnroot/jsonschemaphpv/trunk@4 14558f9d-7ea9-46ec-92da-52a2cad6a683

Author: bruno_p_reis