rb capabilites spec now expects MicrosoftEdge instead of edge

Update spec for fix to #1002, which changed the browser_name from
"edge" to "MicrosoftEdge".

Author: chrismohr

rb/spec/unit/selenium/webdriver/remote/capabilities_spec.rb

@@ -37,7 +37,7 @@ module Remote
 
         it "has default capabilities for Edge" do
           caps = Capabilities.edge
-          caps.browser_name.should == "edge"
+          caps.browser_name.should == "MicrosoftEdge"
         end
 
         it "has default capabilities for Firefox" do