Install libmicrohttpd which are used for (currently disabled) functional
tests).
Install glibc-locale to get the locales.
Unit test for `prof_whole_occurrences_tests` uses UTF-8 character and
fails without proper locale being set.
Travis supports only quite old Ubuntu releases.
They don't ship with libsignal-protocol-c and not with a recent enough
libgrcypt.
We could build libsignal-protocol-c manually but for libgcrypt it's more
annoying.
Let us switch to Docker and use openSUSE Tumbleweed, which is rolling
release) and thus have up to date libs.