moved addPaginationToQuery() to crud.utils.js and reused it in map and tile_set cruds
added url validation for city_url in map.config.js
new method getMapsCountQuery() in map.crud.js
moved response messages for map.crud.js to config
cleaned getMap()
simplified buildSort() function
addressed CR comments for tile_set.crud.js
addressed CR comments for tile_set.utils.js
removed unused function and unused variable