Add and apply RSpec/BeEq rubocop rule

This rule was added in rubocop-rspec 2.9.0. Once again, we were applying
it about 50% of the time.

spec/helpers/application_helper_spec.rb

@@ -5,21 +5,21 @@ describe ApplicationHelper do
     it "is true if user is the author" do
       user = create(:user)
       proposal = create(:proposal, author: user)
-      expect(author_of?(proposal, user)).to eq true
+      expect(author_of?(proposal, user)).to be true
     end
 
     it "is false if user is not the author" do
       user = create(:user)
       proposal = create(:proposal)
-      expect(author_of?(proposal, user)).to eq false
+      expect(author_of?(proposal, user)).to be false
     end
 
     it "is false if user or authorable is nil" do
       user = create(:user)
       proposal = create(:proposal)
 
-      expect(author_of?(nil, user)).to eq false
-      expect(author_of?(proposal, nil)).to eq false
+      expect(author_of?(nil, user)).to be false
+      expect(author_of?(proposal, nil)).to be false
     end
   end
 end