initialize .travis.yml

.travis.yml

+language: cpp
+
+sudo: required
+
+install:
+    - sudo apt-get install -qq libgflags-dev libprotobuf-dev libprotoc-dev protobuf-compiler libleveldb-dev
+    - sh config_brpc.sh --headers=/usr/include --libs=/usr/lib
+    - make -sj8
+
+script:
+    - cd example/echo_c++
+    - make