project: Add Travis CI configuration

Doxygen uses the README.md as generated mainpage but fails with image
links. Therefore for the moment the status badges are not clickable.

.travis.yml

@@ -0,0 +1,44 @@
+jobs:
+  include:
+    - language: cpp
+      before_install:
+        - pip install --user cpp-coveralls
+      addons:
+        apt:
+          sources:
+            - ubuntu-toolchain-r-test
+          packages:
+            - cmake
+            - doxygen
+            - g++-6
+            - ninja-build
+      script:
+        - mkdir build && cd build
+        - CXX=/usr/bin/g++-6 CC=/usr/bin/gcc-6
+          cmake -DCMAKE_BUILD_TYPE=Coverage -G Ninja ..
+        - cmake --build .
+        - cmake --build . --target test
+        - cmake --build . --target dox
+      after_success:
+        - coveralls -r $TRAVIS_BUILD_DIR -b $TRAVIS_BUILD_DIR/build
+                    --gcov '/usr/bin/gcov-6' --gcov-options '\-lp'
+                    -i lib -e target
+    - language: cpp
+      addons:
+        apt:
+          packages:
+            - avr-libc
+            - cmake
+            - ninja-build
+      script:
+        - mkdir build && cd build
+        - cmake -DCMAKE_TOOLCHAIN_FILE=../cmake/avr/generic-gcc-avr.cmake
+                -DBUILD_DOCUMENTATION=OFF
+                -DTARGET_CONFIGURATION=arduino
+                -DAVR_MCU=atmega328p
+                -G Ninja ..
+        - cmake --build .
+    - language: python
+      python: 3.6
+      install: pip install tox
+      script: cd tools && tox

README.md

@@ -1,5 +1,9 @@
 atMETEO - An ATmega based weather station
 =========================================
+<!-- @cond Hide from Doxygen-->
+[![Build Status](https://travis-ci.org/fetzerch/atMETEO.svg?branch=master)](https://travis-ci.org/fetzerch/atMETEO)
+[![Coverage Status](https://coveralls.io/repos/github/fetzerch/atMETEO/badge.svg)](https://coveralls.io/github/fetzerch/atMETEO)
+<!-- @endcond -->
 
 As its name implies *atMETEO* is a project for collecting and measuring weather
 related data from different sensors. The data is being collected by an ATmega