[Merge] with upstream and development changes

.travis.yml

CMakeLists.txt

Dockerfile

HACKING.md

README.md

lang/calamares_ar.ts

lang/calamares_ast.ts

lang/calamares_bg.ts

lang/calamares_ca.ts

lang/calamares_cs_CZ.ts

lang/calamares_da.ts

lang/calamares_de.ts

lang/calamares_el.ts

lang/calamares_en.ts

lang/calamares_en_GB.ts

lang/calamares_es.ts

lang/calamares_es_ES.ts

lang/calamares_es_MX.ts

lang/calamares_es_PR.ts

lang/calamares_et.ts