Changes quotes so that path will be set appropriately on multiple runs

plugins/npm/npm.plugin.zsh

@@ -14,4 +14,4 @@ alias npmS="npm i -S "
 alias npmD="npm i -D "
 # Execute command from node_modules folder based on current directory
 # i.e npmE gulp
-alias npmE="PATH=$(npm bin):$PATH"
+alias npmE='PATH="$(npm bin)":"$PATH"'