The 'find' command was not installed in our minimal Fedora 26
and 27-based Docker images. This resulted in a non-fatal error
when performing a 'make clean'. This commit adds this utility
(available in the 'findutils' package).
Signed-off-by: Geoffroy Van Cutsem <geoffroy.vancutsem@intel.com>
Enable Travis CI testing for the following development host OSs:
* Clearlinux
* Ubuntu 16.04
* Fedora 26
Signed-off-by: Geoffroy Van Cutsem <geoffroy.vancutsem@intel.com>