initial progress on paste image support
TODO: insert hidden contenteditable div inside targetElement (to support FF & possibly other browsers), option dialog for user to set name of pasted image (FU only)
Promises; Allow FUB integrator to provide name for pasted image.  TODO: Restrict to image media types; Overridable pasted image name prompt for FU integrators; Unit tests.
treat paste received callback like any other callback
a few paste image bugfixes
only delegate to default callback if triggerHandler does not result in a defined return value if the callback is promissory
ensure onPasteReceived callback returns promise
process all pasted images
add option in FineUploader mode that allow the integrator to ask users to name the pasted image, also overridable prompt dialog
readme updates
emphasis
showPrompt should also be promissory
callback documentation adjustment
less wordy
#487 - support uploading images by paste