// http://www.abeautifulsite.net/whipping-file-inputs-into-shape-with-bootstrap-3/
$(document)
    .on('change', '.btn-file :file', function () {
        var input = $(this),
            numFiles = input.get(0).files ? input.get(0).files.length : 1,
            label = input.val().replace(/\\/g, '/').replace(/.*\//, '');
        input.trigger('fileselect', [numFiles, label]);
    });