Replace _.map with Array.map
Replace _.map with Array.map

Array.map is used elsewhere in the library.  This removes the
undocumented dependency on underscore.js

eXa-online/ember-resource,staugaard/ember-resource,eXa-online/ember-resource,avdv/ember-resource,staugaard/ember-resource,zendesk/ember-resource,zendesk/ember-resource,avdv/ember-resource