Try to adapt travis to postgresql

.travis.yml

 language: node_js
 
 node_js:
-  - "4.6"
-  - "6.9"
+  - "4"
+  - "6"
 
 env:
   - CXX=g++-4.8
@@ -13,11 +13,12 @@ addons:
       - ubuntu-toolchain-r-test
     packages:
       - g++-4.8
+  postgresql: "9.4"
 
 sudo: false
 
 services:
-  - mongodb
+  - postgresql
 
 before_install: if [[ `npm -v` != 3* ]]; then npm i -g npm@3; fi
 
@@ -29,6 +30,13 @@ before_script:
   - cp ffmpeg-*-64bit-static/{ffmpeg,ffprobe,ffserver} $HOME/bin
   - export PATH=$HOME/bin:$PATH
   - export NODE_TEST_IMAGE=true
+  - psql -c 'create database peertube_test1;' -U postgres
+  - psql -c 'create database peertube_test2;' -U postgres
+  - psql -c 'create database peertube_test3;' -U postgres
+  - psql -c 'create database peertube_test4;' -U postgres
+  - psql -c 'create database peertube_test5;' -U postgres
+  - psql -c 'create database peertube_test6;' -U postgres
+  - psql -c 'create user peertube with password \'peertube\';' -U postgres
 
 after_failure:
   - cat test1/logs/all-logs.log