Outdoor storage is prohibited in all residential zoning districts. In nonresidential districts, no article, object or material shall be kept, stored or displayed outside of the confines of a building unless the same is screened by special planting or fencing and is otherwise approved pursuant to an approval by the Planning Board. No storage area shall be located in a front yard or other yard abutting a street. However, nothing in this section shall be deemed to prohibit the display and sale of seasonal farm produce, specifically-permitted outdoor uses, the outdoor parking or storage of farm machinery or vehicles in use on a farm, or normal and unobtrusive outdoor storage such as the storage of firewood in residential districts.