Added a new parameter az default option to define target element

1- 'target' added as default option and it's value set to this
2- A variable named '$target' defined
3- In the function named 'insertNav', '$container' replaced with '$target'
4- '$container' in lines 199 and 222 has been changed w/ '$target'
5- Now it works and 'appendTo', 'prependTo' also can set as 'location' value