test: Add fedora28 and ubuntu1604 dockerfiles

These dockerfiles can be used to run taskwarrior's test suite on the
respective platforms using the following commands:

$ cd taskwarrior.git
$ docker build -t test-tw-fedora28 -f test/docker/fedora28 .
$ docker run test-tw-fedora28

For ubuntu, replace fedora28 with ubuntu1604.

test/docker/fedora28

@@ -0,0 +1,26 @@
+FROM fedora:28
+
+RUN dnf update -y
+RUN dnf install python git gcc gcc-c++ cmake make gnutls-devel libuuid-devel -y
+
+# Setup language environment
+ENV LC_ALL en_US.UTF-8
+ENV LANG en_US.UTF-8
+ENV LANGUAGE en_US.UTF-8
+
+# Setup taskwarrior
+ADD . /root/code/
+WORKDIR /root/code/
+RUN git clean -dfx
+RUN git submodule init
+RUN git submodule update
+RUN cmake -DCMAKE_BUILD_TYPE=debug .
+RUN make -j2
+RUN make install
+RUN task --version
+
+# Setup tests
+WORKDIR /root/code/test/
+RUN make
+
+CMD ["bash", "-c", "./run_all ; ./problems ; cat all.log | grep 'not ok'"]

test/docker/ubuntu1604

@@ -0,0 +1,27 @@
+FROM ubuntu:16.04
+
+RUN apt-get update
+RUN apt-get install -y build-essential cmake git uuid-dev libgnutls28-dev
+RUN apt-get install -y python
+
+# Setup language environment
+ENV LC_ALL en_US.UTF-8
+ENV LANG en_US.UTF-8
+ENV LANGUAGE en_US.UTF-8
+
+# Setup taskwarrior
+ADD . /root/code/
+WORKDIR /root/code/
+RUN git clean -dfx
+RUN git submodule init
+RUN git submodule update
+RUN cmake -DCMAKE_BUILD_TYPE=debug .
+RUN make -j2
+RUN make install
+RUN task --version
+
+# Setup tests
+WORKDIR /root/code/test/
+RUN make
+
+CMD ["bash", "-c", "./run_all ; ./problems ; cat all.log | grep 'not ok'"]