Use maven wrapper instead of plain maven

[danielsiwiec]

I'd like to propose the use of Maven wrapper, as explained in this post. There are a few advantages to it:

• Simplifying local development, by removing the need to install maven manually
• Standardizing maven version across all contributors (maven-wrapper.properties)
• Ensuring the build system uses the same maven version as developers
• Simplifying maven version updates across all developers (again, the properties file)