Corrected include in teamslist

Minor correction to one line.
Issue #3 double click on team submit

Added onclick="this.disabled = true;" and can no longer recreate double
skill entry problem.
Issue #1

Using empty() instead of is_null to test date_created
Issue #3 fix for double skills in db

Cleans any player with duplicate skills in Db when displayed.
Merge pull request #4 from Cosworth32/master

Corrected include in teamslist, and issue 1 + 3