Hot code reload: added support for rewiring slotProxy (#3365)
Hot code reload: added support for rewiring slotProxy (#3365)

Adds a function in slotProxy class to transfer rendering capability to
another particle

Builds on prior change of adding disable handle support
PolymerLabs/arcs,PolymerLabs/arcs,PolymerLabs/arcs,PolymerLabs/arcs,PolymerLabs/arcs,PolymerLabs/arcs,PolymerLabs/arcs,PolymerLabs/arcs