Added PyYAML requirement for cpp-coveralls.

Author: kevincon

.travis.yml

@@ -7,6 +7,7 @@ xcode_scheme:
     - Template Framework Project
     - TestsProject
 before_install:
+    sudo pip install PyYAML
     sudo pip install cpp-coveralls
 after_success:
     ./scripts/coveralls.rb --extension m --extension mm --exclude-folder include --exclude-folder TestsProject