Verification issue - Improve assignment of verifiers

[CrisSevilleja]

On page https://butterfly-monitoring.net/admin/filter-edit we assign new veriffiers.

This page needs extra filters to assign more accurate area to verifiers: add all NUTS level
At the moment, only country and NUT level 1 are available. Missing NUT level 2. The way of select the country or NUT is not a drop-down list, being need to write completely the NUT name (not useful), better way on https://butterfly-monitoring.net/elastic/all-records

Also, the visualization of this page is not good, buttons to accept or reject are not well visible

[johnvanbreda]

• I've committed a tweak to the styles so it looks better (but not pushed to the live site yet).
• I've also added NUTs level 2 to the Create a Filter tool on this page. You should not need to type the whole NUTS region name as a list of suggestions should appear if you type the first character or two.