[api - checkouts] Format shipment_attributes neater
[api - checkouts] Provide details of payments attribute structure

Fixes #170
Updated default logo location

Fixes #186
Fixed javascript path

Fixes #186
Add Ansible + Ubuntu guide
Fixing Issue #187: broken links
developer: fix relative links in sidebar
Update basic ep tutorial to relfect most recent endpoint_base features
Add integration api TOC
Fixed state machine link
Actually fixed the state machine link
Update order messages
Correct API available_messages blurb
Mention heroku user-env-compile deployment guides

Otherwise users won't be able to deploy Spree as is currently to heroku.
Restore SpreeConf promo
Fix spreeconf popup style issues
Rename spreeconf banner cookie
Update SpreeConf badge with new image (new styles needed)
Fix styles for spreeconf badge
Fix spreeconf eraly price