add travis integration

.travis.yml

@@ -0,0 +1,23 @@
+language: cpp
+sudo: false
+matrix:
+  include:
+  - compiler: gcc
+    addons:
+      apt:
+        sources:
+        - ubuntu-toolchain-r-test
+        packages:
+        - g++-4.8
+    before_script: export CXX=g++-4.8
+  - compiler: clang
+    addons:
+      apt:
+        sources:
+        - ubuntu-toolchain-r-test
+        - llvm-toolchain-precise-3.8
+        packages:
+        - clang-3.8
+    before_script: export CXX=clang++-3.8
+script:
+- make -C test/modem test