fix(gridster): destroy resize_api
fix(gridster): destroy resize_api

Call  `resize_api.destroy()`  to fix  memory leak.

Closes #473

luke-browning/gridster.js,luke-browning/gridster.js,barneywilliams/gridster.js,Firewall/gridster.js,emartech/gridster.js,stenverbois/gridster.js,zeroedin-bill/gridster.js,zeroedin-bill/gridster.js,luke-browning/gridster.js,dsmorse/gridster.js,M0nter0/gridster.js,barneywilliams/gridster.js,stenverbois/gridster.js,emartech/gridster.js,Firewall/gridster.js,zeroedin-bill/gridster.js,dsmorse/gridster.js,stenverbois/gridster.js,M0nter0/gridster.js,dsmorse/gridster.js,M0nter0/gridster.js,Firewall/gridster.js,emartech/gridster.js