net-firewall/shorewall*: Bump to v4.5.21.10

The new version will fix:
 - https://bugs.gentoo.org/show_bug.cgi?id=509258
Update .travis.yml
Merge pull request #1 from Whissi/shorewall-4.5.21.10

net-firewall/shorewall*: Bump to v4.5.21.10
net-firewall/shorewall*: QA fixes from the Portage tree