Travis CI: Use ICU 57 backport to Trusty
Travis CI: Use ICU 57 backport to Trusty

google/language-resources,googlei18n/language-resources,google/language-resources,googlei18n/language-resources,googlei18n/language-resources,googlei18n/language-resources,google/language-resources,google/language-resources,googlei18n/language-resources,googlei18n/language-resources,google/language-resources,google/language-resources