Add Trevis CI support

Add Travis CI support to GitHub repo.

After every push to master, Travis will build
the sources directly from GitHub repo according
to .travis.yml and verify everything is ok.

No functional change.

.travis.yml

@@ -0,0 +1,22 @@
+language: cpp
+compiler: g++
+sudo: required
+
+before_install:
+  - sudo add-apt-repository -y ppa:ubuntu-toolchain-r/test
+  - sudo apt-get update -qq
+
+install:
+  - sudo apt-get install -qq g++-4.8
+  - sudo update-alternatives --install /usr/bin/g++ g++ /usr/bin/g++-4.8 90
+
+branches:
+  only:
+   - master
+
+before_script:
+  - cd src
+
+script:
+  - make clean && make build ARCH=x86-64 COMP=gcc && ./stockfish bench 2>&1 >/dev/null | grep 'Nodes searched'
+  - make clean && make build ARCH=x86-32 COMP=gcc && ./stockfish bench 2>&1 >/dev/null | grep 'Nodes searched'