Add drush as a default installed utility

.travis.yml

@@ -10,7 +10,7 @@ env:
       MACHINE_NAME: drupalvm
       IP: 192.168.88.88
       DRUPALVM_DIR: /var/www/drupalvm
-      DRUSH_BIN: "${DRUPALVM_DIR}/drupal/vendor/drush/drush/drush"
+      DRUSH_BIN: drush
       TEST_INSTALLED_EXTRAS: true
   matrix:
     # Defaults - Ubuntu 16.04.
@@ -25,7 +25,6 @@ env:
       run_opts: "--privileged"
       local_config: tests/ubuntu-16-nginx.config.yml
       config_dir: /var/www/drupalvm/config
-      DRUSH_BIN: "/usr/local/bin/drush"
     # PostgreSQL - Ubuntu 16.04.
     - type: postgresql
       distro: ubuntu1604
@@ -34,6 +33,7 @@ env:
       local_config: tests/ubuntu-16-postgresql.config.yml
       config_dir: /var/www/drupalvm/config
       TEST_INSTALLED_EXTRAS: false
+      DRUSH_BIN: "${DRUPALVM_DIR}/drupal/vendor/drush/drush/drush"
     # Defaults - CentOS 7.
     - type: centos
       distro: centos7

default.config.yml

@@ -192,9 +192,9 @@ installed_extras:
   - adminer
   # - blackfire
   - drupalconsole
+  - drush
   # - elasticsearch
   # - java
-  # - drush
   - mailhog
   # - memcached
   # - newrelic

tests/ubuntu-16-nginx.config.yml

@@ -5,13 +5,3 @@ drupalvm_webserver: nginx
 build_makefile: true
 build_composer_project: false
 drupal_core_path: "/var/www/drupalvm/drupal"
-
-drush_path: "/usr/local/bin/drush"
-installed_extras:
-  - adminer
-  - drupalconsole
-  - mailhog
-  - pimpmylog
-  - varnish
-  - xhprof
-  - drush