Use Automake's pkginclude feature

Automake has a magic prefix for the common $(includedir)/$(PACKAGE)
idiom that was in use previously.
Add a draft .yml for Travis-CI
Merge pull request #28 from RhysU/pkginclude

Use Automake's pkginclude feature
Merge pull request #29 from RhysU/travis_ci

Add a draft .yml for Travis-CI