endpoint for uploading derivative files
download project specific derivatives form project#derivatives_download
removed derivs folder from repo
uploaded derivs now have thumbnails
fixes where derivative field was always false
added derivatives folder to gitignore
deleted fixtures folder, fixtures moved to models
adds locked property for terms
fixes terms delete ability
fixes term locked on update
Merge branch 'terms-lock-dgm' into 'develop'

Terms lock dgm

locked feature

See merge request !16
Preview image support for .pdf
Merge `develop` into `derivatives-dgm`
Fix file description path
fix cwb load path for tasks
binstubs
Misc. derivatives changes
Delete derivatives on project delete
Remove background_init rescue logs

Think these might be what the background job sometimes chokes on
Name the derivates zip according to the task desc