Find the largest perimeter of an island given a 2 dimensional array of 1's and 0's representing land and water respectively.

Land = 1
Water = 0
Island = contiguous 1's that are adjacent to other 1's to the left, right, up, or down

Edge of an island = any 1 that is adjacent to a 0 OR grid boundary to the left, right, up, or down

Perimeter = total # of 1's on the edge of an island

Example 1:

Input:
[[1, 0, 1, 1, 1],
 [1, 0, 1, 1, 1],
 [0, 1, 0, 1, 1]]

Output: 7 (Island on the right)

Example 2:

Input:
[[0, 0, 0, 0, 0, 0, 0],
 [0, 1, 0, 1, 1, 1, 0],
 [0, 1, 0, 1, 1, 1, 0],
 [0, 0, 1, 1, 1, 1, 0],
 [0, 0, 0, 0, 0, 0, 0]]

Output: 9 (Island on the right)