Add necessary integration pieces for Travis CI

- .travis.yml: provides the metadata for describing how the project
  should be built and tested.
- travis/build.sh: builds the project.
- travis/test.sh: tests the project.

This commit adds support for the following matrix:
- Ubuntu 14.04 LTS (trusty) x {clang,gcc} x {ext4}
- Ubuntu 16.04 LTS (xenial) x {clang,gcc} x {ext4}

Some initial scaffolding is filled in for OSX, but I haven't fully
tested out the Travis CI integration, so I'm not yet throwing that
switch. It seems to be beta supported, per
https://docs.travis-ci.com/user/multi-os/ , so I might need to run the
builds on my Mac hardware for the time being.

Some administrative switches need to be flipped in order for this change
to be made effective, but this has proven successful on my fork
(yaneurabeya/pjdfstest).

Fixes GitHub issue # 12

Capture more information for FreeBSD, Linux, and OSX

FreeBSD isn't supported with Travis CI, but Linux definitely is, and OSX
is partially supported.

.travis.yml

@@ -0,0 +1,21 @@
+language: c
+sudo: required
+
+matrix:
+    include:
+        - os: linux
+          compiler: clang
+          dist: trusty
+        - os: linux
+          compiler: gcc
+          dist: trusty
+        - os: linux
+          compiler: clang
+          dist: xenial
+        - os: linux
+          compiler: gcc
+          dist: xenial
+
+script:
+    - ./travis/build.sh
+    - ./travis/test.sh

travis/build.sh

@@ -0,0 +1,6 @@
+#!/bin/sh
+
+set -e
+
+cd $(dirname $0)/..
+make

travis/test.sh

@@ -0,0 +1,27 @@
+#!/bin/sh
+
+set -ex
+
+cd $(dirname $0)/..
+
+df .
+uname -a
+
+case "$(uname)" in
+Darwin)
+	sw_vers -productVersion
+	mount
+	;;
+FreeBSD)
+	mount -p
+	;;
+Linux)
+	for release_file in /etc/lsb-release /etc/os-release; do
+		echo "$release_file.. ->"
+		cat $release_file
+	done
+	mount
+	;;
+esac
+
+sudo prove -rv .