Improve .no-js Nav behavior

[salcode]

@bryanwillis

Did some nice work in the wiki https://github.com/salcode/bootstrap-genesis/wiki/How-to-enable-features-when-javascript-is-disabled, where he added the following code

.no-js .dropdown a:focus ~ .dropdown-menu {
    display: block;
}
@media (max-width: 767px ) {
    .no-js .navbar-nav .dropdown-toggle:focus ~ .dropdown-menu {
    position: static;
    float: none;
    width: auto;
    margin-top: 0;
    background-color: transparent;
    border: 0;
    -webkit-box-shadow: none;
    box-shadow: none;
    display: block;
    }
    .no-js .navbar-header:hover ~ .collapse,
    .no-js .navbar-header ~ .collapse:hover {
    display: block;
    overflow-y: visible;
    overflow-x: visible;
    }
}

which seems to be a superior to the code added in 93cef771e8787

Bryan's code more closely mimics the original behavior (when JS is enabled) and I think we should use it instead of the current code.