The component itself does not offer any configuration options for this. Instead you can use CSS to achieve the style you want. The blue border for example is caused by the CSS the Bootstrap framework provides.

You can add something like this to your templates CSS file:

a.thumbnail:hover, a.thumbnail:focus {
    border-color: #08c;
    -webkit-box-shadow: 0 1px 4px rgba(0,105,214,0.25);
    -moz-box-shadow: 0 1px 4px rgba(0,105,214,0.25);
    box-shadow: 0 1px 4px rgba(0,105,214,0.25);
}

Please send me a link to your site.

Maybe you want to add this as well. It's just a copy from the bootstrap styles. It's totally possible that I missed something.

.thumbnail {
border: 1px solid #ddd;
-webkit-box-shadow: 0 1px 3px rgba(0,0,0,0.055);
-moz-box-shadow: 0 1px 3px rgba(0,0,0,0.055);
box-shadow: 0 1px 3px rgba(0,0,0,0.055);
-webkit-transition: all .2s ease-in-out;
-moz-transition: all .2s ease-in-out;
-o-transition: all .2s ease-in-out;
transition: all .2s ease-in-out;
}