Fix #2108 - Fix gif uploads (#2171)

* Fix #2108 - Fix gif uploads
Add specs for media attachment gifv conversion

* Add ffmpeg to travis

* Make travis install ffmpeg, not libav

* Switch travis to trusty

spec/models/media_attachment_spec.rb

@@ -1,5 +1,27 @@
 require 'rails_helper'
 
 RSpec.describe MediaAttachment, type: :model do
+  describe 'animated gif conversion' do
+    let(:media) { MediaAttachment.create(account: Fabricate(:account), file: attachment_fixture('avatar.gif')) }
 
+    it 'sets type to gifv' do
+      expect(media.type).to eq 'gifv'
+    end
+
+    it 'converts original file to mp4' do
+      expect(media.file_content_type).to eq 'video/mp4'
+    end
+  end
+
+  describe 'non-animated gif non-conversion' do
+    let(:media) { MediaAttachment.create(account: Fabricate(:account), file: attachment_fixture('attachment.gif')) }
+
+    it 'sets type to image' do
+      expect(media.type).to eq 'image'
+    end
+
+    it 'leaves original file as-is' do
+      expect(media.file_content_type).to eq 'image/gif'
+    end
+  end
 end