Insulate installer from changes in BitBucket CDN architecture, fixes #161

Hello @nicks, 

Please review the following commits I made in branch 'dpup-cdn'.

8f38dbac5784c762963c2f9277286b593014bc7e (2014-05-23 10:05:17 -0700)
Insulate installer from changes in BitBucket CND architecture, fixes #161

R=@nicks