suppress memory leak warnings for python tests

Now that travis does not fail, the allow_failure flag for the
clang-compiler job can be removed.

.travis.yml

@@ -19,7 +19,6 @@ script:
 matrix:
   allow_failures:
     - os: osx
-    - compiler: clang
   fast_finish: true
   include:
     - os: linux

lsan.supp

@@ -0,0 +1,5 @@
+leak:python2.7
+leak:libfontconfig.so
+leak:libglib-2.0.so
+leak:libIlmImf-2_2.so
+leak:libstdc++.so