MEDIUM: enable travis-ci builds

currently only xenial/clang build is enabled. osx and xenial/gcc
will be enabled later.

travis-ci is cloud based continuous integration, builds will be
started automatically if they are enabled for certain repo or fork.

Signed-off-by: Ilya Shipitsin <chipitsine@gmail.com>

.travis.yml

@@ -0,0 +1,24 @@
+sudo: required
+dist: xenial
+
+language: c
+
+matrix:
+  include:
+#  - os: linux
+#    compiler: gcc
+#    env: TARGET=linux2628
+  - os: linux
+    compiler: clang
+    env: TARGET=linux2628 USE_THREAD=1 USE_OPENSSL=1 USE_PCRE=1 USE_ZLIB=1 USE_GETADDRINFO=1
+#  - os: osx
+#    compiler: clang
+#    env: TARGET=osx SSL_LIB=/usr/local/opt/openssl/lib SSL_INC=/usr/local/opt/openssl/include TMPDIR=/var/tmp
+
+install:
+  - git clone https://github.com/VTest/VTest.git ../vtest
+  - make -C ../vtest
+
+script:
+  - make CC=$CC V=1 TARGET=$TARGET USE_THREAD=${USE_THREAD} USE_OPENSSL=${USE_OPENSSL} USE_PCRE=${USE_PCRE} USE_ZLIB=${USE_ZLIB} USE_GETADDRINFO=${USE_GETADDRINFO}
+  - make reg-tests PATH=${PATH}:${PWD}/../vtest VTEST_PROGRAM="../vtest/vtest -v"