Support upload fields for multiple files

[Guite]

A new upload field property should allow to have multiple uploads.

Generator implementation should treat this as an array field instead of using a text field.
Also the additional array field for meta data should become an array of arrays in those cases.

Async implementation of #122 should be enhanced to support lists with multiple files, too.

Reference code is available.

[espaan]

For reference also this ticket in SimpleMedia https://github.com/zikula-ev/SimpleMedia/issues/24
I'm trying to get http://blueimp.github.com/jQuery-File-Upload/ working. Most of this is based on jQuery, which makes the combination with the prototypes scripts a little harder.

[cmfcmf]

@espaan @Guite I recently tried to get the same one working. This is really difficult :-(

[rallek]

would be great to have this option included in MOST so users like me can use it as well ;-)

[espaan]

It's getting easier as we migrate from prototype to full jQuery. Most scripts use jQ and running that together with prototype scripts was not straight forward for me, you need no-conflict, but not all scripts are prepared for that it seems. But getting something general in MOST woudl indeed be really great.

[rallek]

as more as I dive deeper into module design with MOST I am missing this feature more and more! If I could vote it would be part of 0.6.1 ;-)

[rallek]

the solution of https://github.com/cmfcmf/MediaModule could be reference :-)

[Guite]

A new property multiple is being added as part of #541. This ticket is left open for additional UI amendments afterwards.

[Guite]

Just implemented a multi upload based on https://www.dropzonejs.com/ for two MOST-based modules. Maybe this can be reused as a foundation for a generic support. But in my use case each image is stored as a separate entity.