Add CMake build to Travis config.
Add CMake build to Travis config.

firepick1/jansson,akheron/jansson,bstarynk/jansson,akheron/jansson,firepick1/jansson,bstarynk/jansson,npmccallum/jansson,liu3tao/jansson,chrullrich/jansson,slackner/jansson,markalanj/jansson,slackner/jansson,OlehKulykov/jansson,markalanj/jansson,akheron/jansson,npmccallum/jansson,wirebirdlabs/featherweight-jansson,OlehKulykov/jansson,liu3tao/jansson,AmesianX/jansson,Mephistophiles/jansson,AmesianX/jansson,Mephistophiles/jansson,wirebirdlabs/featherweight-jansson,Vorne/jansson,Vorne/jansson,bstarynk/jansson,markalanj/jansson,firepick1/jansson,chrullrich/jansson