Install asterisk to run functional test

Author: clue

.travis.yml

@@ -3,7 +3,9 @@ php:
   - 5.3
   - 5.6
   - hhvm
-before_script:
+install:
+  - sudo apt-get install -y asterisk
+  - export LOGIN='user:pass@localhost'
   - composer install --prefer-source --no-interaction
 script:
   - phpunit --coverage-text