Configure MySQL connector to not try to use SSL.

This removes the following warning from the logs:

WARN: Establishing SSL connection without server's identity verification is not recommended.
According to MySQL 5.5.45+, 5.6.26+ and 5.7.6+ requirements SSL connection must be established by
default if explicit option isn't set. For compliance with existing applications not using SSL the
verifyServerCertificate property is set to 'false'. You need either to explicitly disable SSL by
setting useSSL=false, or set useSSL=true and provide truststore for server certificate verification.

Fix #420

Author: php-coder

src/main/resources/application-prod.properties

@@ -1,6 +1,6 @@
 spring.profiles: prod
 
-spring.datasource.url: jdbc:mysql://localhost:3306/mystamps?logger=com.mysql.jdbc.log.Slf4JLogger
+spring.datasource.url: jdbc:mysql://localhost:3306/mystamps?logger=com.mysql.jdbc.log.Slf4JLogger&useSSL=false
 spring.datasource.username: mystamps
 spring.datasource.password: q1
 spring.datasource.driver-class-name: com.mysql.jdbc.Driver

src/main/resources/application-travis.properties

@@ -1,6 +1,6 @@
 spring.profiles: travis
 
-spring.datasource.url: jdbc:mysql://localhost:3306/mystamps?logger=com.mysql.jdbc.log.Slf4JLogger
+spring.datasource.url: jdbc:mysql://localhost:3306/mystamps?logger=com.mysql.jdbc.log.Slf4JLogger&useSSL=false
 spring.datasource.username: travis
 spring.datasource.password:
 spring.datasource.driver-class-name: com.mysql.jdbc.Driver