(#43) Include OpenLayers exclusively through Bower.

Before this commit, the application was referencing OpenLayers from three different sources:

- Through Bower.
- Through a local copy in the "src/vendor" directory.
- Remotely via openlayers.org.

I removed the "src/vendor" copy and references to openlayers.org. A local single-file copy of OpenLayers is now being built using OpenLayers' build system. I confirmed via Chrome's network monitor that OpenLayers is now being included in our compiled client.js exclusively.