Remove legend-layer-menu as a Bower Dependency from compare

[syntagmatic]

Would replace #217 by pulling in the legend-layer-menu directly into the Compare repo, eliminating it as a Bower dependency.

This will make it easier for new developers to make changes in the future.

Afterwards berkeley-gif's version is updated, we could delete this repository to reduce the complexity of the project.

https://github.com/stamen/legend-layer-menu

[syntagmatic]

Resolved here. Still need to update berkeley-gif's version of ecoengine-compare before we can deprecate the legend-layer-menu repo

stamen/ecoengine-compare@9367c7b