To make the jumbotron full width, and without rounded corners, place
it outside all .containers and instead add a .container within.
<div class="jumbotron">
<div class="container">
...
</div>
</div>
See Docs
And since you're using Bootstrap-Material, you can use the built in classes to add color (this is dependent on the material-fullpalette.css, not material.css, See Docs)
See Working Example Snippets.
$.material.init()
/*ADD YOURSELF*/
.jumbotron.jumbo-red {
background: red;
}
<link href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/css/bootstrap.min.css" rel="stylesheet" />
<link href="https://cdnjs.cloudflare.com/ajax/libs/bootstrap-material-design/0.4.4/css/material-fullpalette.min.css" rel="stylesheet" />
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/js/bootstrap.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/bootstrap-material-design/0.4.4/js/ripples.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/bootstrap-material-design/0.4.4/js/material.min.js"></script>
<div class="well">Your Own CSS for Color</div>
<div class="jumbotron jumbo-red">
<div class="container">
<h1>Full Width Layout</h1>
<p class="lead">The Bootstrap 3 grid is fluid only. This example shows how to use a custom container to create a fixed width layout.</p>
<p><a class="btn btn-large btn-success" href="#" target="ext">More
Examples</a>
</p>
</div>
</div>
<hr>
<div class="well">Material CSS for Color</div>
<div class="jumbotron jumbotron-material-red-A700">
<div class="container">
<h1>Full Width Layout</h1>
<p class="lead">The Bootstrap 3 grid is fluid only. This example shows how to use a custom container to create a fixed width layout.</p>
<p><a class="btn btn-large btn-material-green" href="#" target="ext">More
Examples</a>
</p>
</div>
</div>