Remove defer from material.min.js

[jkaan]

Hello there!

I ran into an issue when using your library, which will probably be solved by just changing this in the README.md

I do not have the most experience with JavaScript and asynchronous loading, so this might be solvable in a different way.

Explanation of the problem: Adding defer would allow this script to execute after the getmdl-select.js script. For me the problem was that I was setting the data-selected=true, but in the setSelectedItem function it was requesting dropdown.MaterialTextField, which was not there yet because the material.min.js did not execute yet.