minor #491 run tests against php 7.1 (fbourigault)

This PR was merged into the master branch.

Discussion
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run tests against php 7.1

Enable php 7.1 in travis-ci matrix.

Commits
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0efcbc0 run tests against php 7.1

Author: javiereguiluz

.travis.yml

@@ -11,6 +11,7 @@ matrix:
     - php: 5.5
     - php: 5.6
     - php: 7.0
+    - php: 7.1
     - php: hhvm
   allow_failures:
     - php: hhvm