Merge pull request #153 from dimagi/develop

merge develop to master
pass in sessionid explicitly to YUI uploader

get around Django 1.5 change to use HttpOnly cookie for session
Merge pull request #155 from dimagi/hotfix-multimedia

pass in sessionid explicitly to YUI uploader
update confluence links on app builder
Merge pull request #157 from dimagi/updateHelpLinks

update confluence links on app builder
Merge pull request #156 from mwhite/develop

Add "Ignore But Retain" plugin
Merge branch 'develop' of github.com:dimagi/Vellum into develop
Merge branch 'master' of github.com:dimagi/Vellum into develop