Update Travis config

I have re enabled the llvm toolchain in the travis config. The problems
with llvm apt repository have been resolved.

Using cmake 3.6.2 for travis builds

Signed-off-by: Christian Rapp <[email protected]>

.travis.yml

@@ -31,26 +31,26 @@ matrix:
           packages:
             - g++-6
       env: COMPILER=g++-6
-    #- os: linux
-      #compiler: clang
-      #addons:
-        #apt:
-          #sources:
-            #- ubuntu-toolchain-r-test
-            #- llvm-toolchain-precise-3.6
-          #packages:
-            #- clang-3.6
-      #env: COMPILER=clang++-3.6
-    #- os: linux
-      #compiler: clang
-      #addons:
-        #apt:
-          #sources:
-            #- ubuntu-toolchain-r-test
-            #- llvm-toolchain-precise-3.7
-          #packages:
-            #- clang-3.7
-      #env: COMPILER=clang++-3.7
+    - os: linux
+      compiler: clang
+      addons:
+        apt:
+          sources:
+            - ubuntu-toolchain-r-test
+            - llvm-toolchain-precise-3.7
+          packages:
+            - clang-3.7
+      env: COMPILER=clang++-3.7
+    - os: linux
+      compiler: clang
+      addons:
+        apt:
+          sources:
+            - ubuntu-toolchain-r-test
+            - llvm-toolchain-precise-3.8
+          packages:
+            - clang-3.8
+      env: COMPILER=clang++-3.8
     - os: osx
       compiler: clang
       osx_image: xcode6.4
@@ -65,8 +65,8 @@ matrix:
 install:
   - |
     if [[ "${TRAVIS_OS_NAME}" == "linux" ]]; then
-      CMAKE_URL="https://cmake.org/files/v3.5/cmake-3.5.2-Linux-x86_64.sh"
-      CMAKE_INSTALLER="cmake-3.5.2-Linux-x86_64.sh"
+      CMAKE_URL="https://cmake.org/files/v3.6/cmake-3.6.2-Linux-x86_64.sh"
+      CMAKE_INSTALLER="cmake-3.6.2-Linux-x86_64.sh"
       wget --no-check-certificate --quiet -O ${CMAKE_INSTALLER} - ${CMAKE_URL}
       sh ${CMAKE_INSTALLER} --prefix=$HOME --exclude-subdir
     else