Add Feature Compare plugin

Given a configuration of URLs that are capable of being displayed
as ESRI FeatureLayers, this plugin allows you to select features
from the map and compare their attributes.  It supports state and
export features from the framework, but has some additional
features to be added (support for older browsers, formatting of
attribute values) that will be added feedback from the client
Merge pull request #180 from mmcfarland/topic/watershed-compare

Add Feature Compare plugin