Move composer setup to separate phase

Signed-off-by: Michal Čihař <michal@cihar.com>

.travis.yml

@@ -28,10 +28,9 @@ env:
 before_script:
   - export PATH=~/.composer/vendor/bin/:$PATH
   - mysql -uroot -e "SET PASSWORD = PASSWORD('$TESTSUITE_PASSWORD')" ;
+  - composer install --dev --no-interaction
   - set -e ; if [[ -z "$LINT" ]] ; then
 
-    composer install --dev --no-interaction ;
-
     if [[ $TRAVIS_PHP_VERSION != "hhvm" ]] ; then
 
     git clone --depth=1 git://github.com/zenovich/runkit.git ;