fix Travis locale

we need C locale for number formatting tests
we need English language (English messages are extected)
we need UTF-8 support for processing non-ASCII texts when sending `coveralls` report

.travis.yml

@@ -7,14 +7,20 @@ before_install:
     - wget https://raw.githubusercontent.com/yast/yast-devtools/master/travis-tools/travis_setup.sh
     - sh ./travis_setup.sh -p "rake yast2-core yast2-devtools yast2-testsuite yast2-ruby-bindings yast2 yast2-pkg-bindings" -g "rspec:2.14.1 yast-rake gettext simplecov coveralls rubocop:0.29.1"
 script:
-    - export LANG=C
-    - export LC_ALL=C
+    - locale
+    - locale LC_NUMERIC
+    - export LANG=en_US.UTF-8
+    - export LC_NUMERIC=C
+    - locale
+    - locale LC_NUMERIC
+    - LC_NUMERIC=C locale LC_NUMERIC
+    - LC_ALL= LC_NUMERIC=C locale LC_NUMERIC
     - rake check:pot
     - rubocop
     - make -s -f Makefile.cvs
     - make -s
     - sudo make -s install
     - make -s check
     # make test coverage report
-    - COVERAGE=1 rake test:unit
+    - LC_NUMERIC=C COVERAGE=1 rake test:unit