PAN-6 Updating MySQL version in Travis

.travis.yml

@@ -4,12 +4,20 @@ services:
 
 install: true
 
+addons:
+  apt:
+    sources:
+      - mysql-5.7-trusty
+    packages:
+      - mysql-server
+      - mysql-client
+
 before_install:
   - chmod +x pandamonium-theorem-prover/gradlew
   - cd pandamonium-theorem-prover
 
 before_script:
-  - mysql -u root -e 'CREATE DATABASE pandamonium;'
+  - mysql -u root -e 'CREATE DATABASE IF NOT EXISTS pandamonium;'
   - mysql -u root pandamonium < persistence/scripts/mysql/local_development.sql
 
 stages: