refactor oembed model

Create Oembed from FilePicker parameters

show image being attached

support adding attachments

upgrade SDK

remove YCM scripts

alpha version of image uploads

fix bug where attachment images were sometimes keyed for nil URLs

Also default to “attachments” field if “childContent” is not available

Add conditional before setting attachment image for a cell

don’t block the UI thread

do not write unnecessary stuff to console

we replace image picker for local files

fix plist

add public plist settings