Update .travis.yml

travis ci is outdated shit.

.travis.yml

@@ -1,7 +1,24 @@
-dist: trusty
-sudo: false
+language: generic
+os: osx
+matrix:
+  include:
+    - os: linux
+      env: COMPILER_NAME=gcc CXX=g++-5 CC=gcc-5
+      addons:
+        apt:
+          packages:
+            - g++-5
+          sources: &sources
+            - llvm-toolchain-precise-3.8
+            - ubuntu-toolchain-r-test
+    - os: linux
+      env: COMPILER_NAME=clang CXX=clang++-3.8 CC=clang-3.8
+      addons:
+        apt:
+          packages:
+            - clang-3.8
+          sources: *sources
 
-language: cpp
 script: make all
 
 compiler: