Web Based Movable Floorplan Addon For Our Storage Management Platform

We need YOU to help us to take our web based storage management system to the next level! We currently have a fixed storage plan that needs to be built by our team for customers and is not able to be customised by them. What we want is a storage plan showing individual units within a warehouse, as at current (see uploaded screen shot), but with the ability to move units around and add units of a set size. This needs to be able to be done from Desktop, Tablet and Smartphone and be easy for end users to change around at any time, with minimal work. Units will also need to be able to have their sized changed by double tapping/clicking them and also to be able to have their unit number changed. This must be a true web based system and integrate with our current platform. The units that go on the plan will need to be linkable and assigned as a unit from our units list, as we currently have. Further explanation can be provided if necessary, but this is the core function of the storage plan, that we want to be able to achieve.