[ WIP ] Element wise matrix multiplication

An Implementation for element wise matrix multiplication for `MatrixSymbol` 
@mrocklin  actually I did want that. This was just the initial model but in the future I will be adding some methods that might require them, moreover every `ElemWise` object has a `function` attribute and a `Matrix` attribute. But I haven't seen them being defined elsewhere in sympy. Should I remove static variables for that reason ?