Checking for duplicate song and user names as well as for unusual charac...

...ters

* Adding checkName function that ensures user can't enter duplicate name for user or song and that only alphanumeric, space, underscore, and dash characters are used in the names
* For printing song names, spaces are removed from names in the id as Jquery doesn't handle spaces. Oriingl name is printed in list and once user clicks on the name, original name is used
* Adding css to change cursor to pointer when mouse is over buttons