TravisCI - install locales before running tests

.travis.yml

@@ -5,6 +5,18 @@ php:
   - 7.0
   - 7.1
 
+before_install:
+  - sudo apt-get install locales
+  - sed -i 's/^# de_DE/de_DE/g; \
+            s/^# es_ES/es_ES/g; \
+            s/^# en_GB/en_GB/g; \
+            s/^# en_US/en_US/g; \
+            s/^# fr_FR/fr_FR/g; \
+            s/^# it_IT/it_IT/g; \
+            s/^# pl_PL/pl_PL/g; \
+            s/^# ru_RU/ru_RU/g;' /etc/locale.gen \
+    && locale-gen
+
 install:
   - composer install