Allow adding and editing of map markers

[skray]

Allow for customized marker icons, either custom uploaded, or select from a list of provided.

• upload icons
• delete icons
• resize icons on selection
• edit icon placement, type, and size on map

[skray]

Look at leaflet.editable instead of leaflet.draw. Looks like there is an open issue on angular-leaflet-directive about having to hack in leaflet.edit, but it looks like it should be doable by setting the defaults on the leafletMapDefaultsProvider?

angular leaflet directive issue 986

https://github.com/tombatossals/angular-leaflet-directive/blob/e346b1487c667374bb5a20b8108701a048423955/src/directives/leaflet.js#L94