LUN-1910: major changes making a base filer file widget that all other filer widgets should extend
* fixed file type checks in get file view
* don't allow images for file fields
* each field should have it's own popup
* only one popup should be opened for one image field
* no need for 'None' when using get
Merge pull request #16 from pbs/LUN-1910

LUN-1910