OPAL-2246: Align filters
OPAL-2254: Set an empty array when there is no attributes
OPAL-2254: Applied the same logic to determine the variable natures as opal-core-api. Fixed some CSS
OPAL-2254: Cleaning code
Merge pull request #436 from emorency/OPAL-2246-filter-quote

OPAL-2254: Applied the same logic to determine the variable's nature as opal-core-api