Remove limitations (rebased onto develop)


This is the same as gh-896 but rebased onto develop.

----

The efforts put into 5.0.3 should allow us to safely remove a few of the https://www.openmicroscopy.org/site/support/omero5/sysadmins/limitations.html items:
 * [x] wildcard search
 * [x] "too many files" on import