Use local gradlew

Instead of requiring to add `cwd` to path, just use `gradlew` from the local folder. This is how most gradle wrapper projects are laid out

plugins/gradle/gradle.plugin.zsh

@@ -82,7 +82,7 @@ _gradlew_tasks () {
   if [ in_gradle ]; then
     _gradle_arguments
     if _gradle_does_task_list_need_generating; then
-     gradlew tasks --all | grep "^[ ]*[a-zA-Z0-9:]*\ -\ " | sed "s/ - .*$//" | sed "s/[\ ]*//" > .gradletasknamecache
+     ./gradlew tasks --all | grep "^[ ]*[a-zA-Z0-9:]*\ -\ " | sed "s/ - .*$//" | sed "s/[\ ]*//" > .gradletasknamecache
     fi
     compadd -X "==== Gradlew Tasks ====" `cat .gradletasknamecache`
   fi