Implement mapping

[epixian]

a Map:

• belongs to: Jobsite
• has many: Geometry
• has fields: id

[epixian]

Database now stores geometry objects, center, and zoom level for display on a Google Map. Can edit existing maps/objects (manually created on CLI), but not yet create new from scratch using the web interface.

Todo:

• map creation from scratch
• implement one-time geocoding of address for initial "ballpark" viewport