Be much more careful about closing files created by pipe.

Previously, it was possible to leak file descriptors (particularly in error
conditions) and eventually run out of them (though you needed to be unlucky to
hit such a condition).
Kill trailing whitespace.
Add Travis configuration file.
Add README.md.
Test Travis status.
Test Travis status.
Test coverity integration in Travis.
Add OpenHUB badge
Merge branch 'master' of github.com:oliv3/extsmail