Travis config that builds C++ tools

Signed-off-by: Rick Altherr <kc8apf@kc8apf.net>

.travis.yml

@@ -0,0 +1,25 @@
+language: cpp
+
+matrix:
+  include:
+    - os: linux
+      dist: trusty
+      compiler: gcc
+      addons:
+        apt:
+          sources:
+            - ubuntu-toolchain-r-test
+          packages:
+            - g++-6
+      env:
+        - MATRIX_EVAL="CC=gcc-6 && CXX=g++-6"
+
+before_install:
+  - eval "${MATRIX_EVAL}"
+
+script:
+  - mkdir -p build
+  - cd build
+  - cmake -DPRJXRAY_BUILD_TESTING=ON ..
+  - make -j 4
+  - ctest