evtest: bump version to 1.31

- update version to 1.31
- correct license to GPLv2+
- change download url to official repository
- remove evtest-capture support (dropped since 1.31)
- change broken project URL to official repository

Signed-off-by: Peter Seiderer <ps.report@gmx.net>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>