Move travis from Ubuntu to docker+openSUSE

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.

.travis.yml

@@ -1,46 +1,10 @@
-dist: xenial
 sudo: required
 language: c
-install:
-    - lsb_release -a
-    - uname -a
-    - sudo apt-get update
-    - sudo apt-get -y install libssl-dev libexpat1-dev libncursesw5-dev libglib2.0-dev libnotify-dev libcurl3-dev libxss-dev libotr5-dev libgpgme11-dev autoconf-archive expect-dev tcl-dev libtool python-dev libgtk2.0-dev libcmocka-dev
-    - git clone git://github.com/boothj5/libmesode.git
-    - cd libmesode
-    - mkdir m4
-    - ./bootstrap.sh
-    - ./configure --prefix=/usr
-    - make
-    - sudo make install
-    - cd ..
-    - rm -rf libmesode
-    - sudo apt-get install libmicrohttpd-dev
-    - git clone git://github.com/boothj5/stabber.git
-    - cd stabber
-    - ./bootstrap.sh
-    - ./configure --prefix=/usr
-    - make
-    - sudo make install
-    - cd ..
-    - rm -rf stabber
-    - git clone https://github.com/signalapp/libsignal-protocol-c.git
-    - cd libsignal-protocol-c
-    - git checkout v2.3.2
-    - mkdir build
-    - cd build
-    - cmake -DBUILD_SHARED_LIBS=1 -DCMAKE_INSTALL_PREFIX=/usr -DCMAKE_BUILD_TYPE=Release ../
-    - make
-    - sudo make install
-    - cd ../../
-    - rm -rf libsignal-protocol-c
-    - wget https://www.gnupg.org/ftp/gcrypt/libgcrypt/libgcrypt-1.7.0.tar.bz2
-    - tar xfv libgcrypt-1.7.0.tar.bz2
-    - cd libgcrypt-1.7.0
-    - ./configure --prefix=/usr
-    - make
-    - sudo make install
-    - cd ..
-    - rm -rf libgcrypt-1.7.0
-    - cat /usr/include/gcrypt.h
-script: ./travis-build.sh
+services:
+  - docker
+
+before_install:
+  - docker build -f Dockerfile -t profanity .
+
+script:
+- docker run -it profanity ./travis-build.sh