Added prepend, append & wrap method.
Added prepend, append & wrap method.

jmenges/cakephp3-bootstrap-helpers,ypnos-web/cakephp3-bootstrap-helpers,leoruhland/cakephp3-bootstrap3-helpers,Casmo/cakephp3-bootstrap-helpers,idleog/cakephp3-bootstrap3-helpers,lcp0578/cakephp3-bootstrap-helpers,raul338/cakephp3-bootstrap3-helpers,Wouter0100/cakephp3-bootstrap-helpers,Holt59/cakephp3-bootstrap-helpers,Holt59/cakephp3-bootstrap3-helpers