The user creation defined in the SQL files was valid for MySQL 5, but
it is no longer supported by MySQL 8+. This commit fixes this error
by using a syntaxis compatible with MySQL 8+.

The project has been updated so that it now supports MySQL 8+
databases.

The project dependencies have been updated, including a change from
WildFly 8.2.1 to 10.1.0. This change affects the project configuration
in several ways, specially in tests configuration.

The README.md file has been updated to reflect the configuration
changes.

The project configuration has been simplified by unifying some part of
the mysql and h2 configurations.

In addition, the project has been configured to allow the execution of
the application with the Maven WildFly plugin.