src/core/lib: remove code that used undeclared functions
src/lib/hardware/vfio: function to check vfio availability
src/apps/vhost/vhost_user: check vfio before test execution
src/apps/intel/intel_app: get pci ids for test from environment variables
src/apps/vhost/vhost_user: get pci id and socket file for test from environment variables
src/core/memory: calculate size in bytes only if varialble is not null
src/Makefile: check exitcode of test
src/Makefile: ci test mode added, fails on error instead of returng 0
.travis.yml: version with make, make test and debug output
src/core/memory: use 'huge allocator' only if available
src/core/memory: use base page size as default value
src/apps/vhost/[vhost|vhost_apps]: run test only if /dev/net/tun exists