Remove tab characters from Travis CI .yml

.travis.yml

@@ -12,16 +12,16 @@ branches:
 addons:
   apt:
     sources:
-      - ubuntu-toolchain-r-test
-	  - george-edison55/cmake-3.x
+      - ubuntu-toolchain-r/test
+      - george-edison55/cmake-3.x
     packages:
       - gcc-5
       - g++-5
       - zlib1g-dev
-	  - build-essential
-	  - libmysqlclient-dev
-	  - liblua5.1-0-dev
-	  - cmake
+      - build-essential
+      - libmysqlclient-dev
+      - liblua5.1-0-dev
+      - cmake
   
 before_script:
   - mkdir build