"Reblog" -> "boost" in more places

A couple of places were using "reblog" rather than "boost" - this updates them to match the web UI

spec/mailers/notification_mailer_spec.rb

@@ -53,12 +53,12 @@ RSpec.describe NotificationMailer, type: :mailer do
     let(:mail) { NotificationMailer.reblog(own_status.account, Notification.create!(account: receiver.account, activity: reblog)) }
 
     it "renders the headers" do
-      expect(mail.subject).to eq("bob reblogged your status")
+      expect(mail.subject).to eq("bob boosted your status")
       expect(mail.to).to eq([receiver.email])
     end
 
     it "renders the body" do
-      expect(mail.body.encoded).to match("Your status was reblogged by bob")
+      expect(mail.body.encoded).to match("Your status was boosted by bob")
     end
   end