travis: install HTTP::Daemon::SSL perl module

which is required for plugins/tests/check_http.t

Signed-off-by: Sven Nierlein <sven@nierlein.de>

.travis.yml

@@ -29,6 +29,9 @@ install:
   - sudo apt-get install -qq --no-install-recommends faketime
   # Trusty related dependencies (not yet provided)
   - sudo apt-get install -qq --no-install-recommends mariadb-client mariadb-server
+  # this perl module is not available as pkg
+  - sudo apt-get install -qq --no-install-recommends cpanminus
+  - cpanm -n HTTP::Daemon::SSL
 
 before_script:
   # ensure we have a test database in place for tests