0.0.4
Added dot'.' notation support to expose/mask methods. The method will try to walk the
chain until it finds the value to expose/mask.

mask( ['this.sub.value'], model );
expose(['this.sub.value', { 'this.sub.value.two' : 'new.position.in.exposed.model' }], model );

If the expose method can not find the value then it will set it as undefined.

One limitation is that the dot notation can not traverse a sub array so model.[ {value:value}, {value:value}]
will not be able to mask the model.value of the two sub models.