Implement window.location redirection script

See `src/shim.html`. The strategy is as follows:

  1.  GET: `host.com/search/q=star`
  1.  nginx tries to serve the file `WWW_ROOT/search/q=star`
  1.  No such file, so nginx responds (should be 301/302) with `shim.html`
  1.  `shim.html` runs its `<script>`, matches `/search/`, and re-writes `window.location` to `/#/search/q=star`
  1.  nginx sees GET: `/`
  1.  nginx returns `index.html`, and the browser still has `location.hash="/#/search/q=star"`
  1. `require.js` load the application, `backbone.router` takes over using `location.hash`

@romanchyla @aholachek :
See in-line comments, especially the point about regex vs string matching and dealing with multiple '#'s. Feedback expected!
i'd prefer to split by origin and then match routes (they can be ordered, the first that matches, wins), like:

```
if (window.location.hash) // we can't handle this
  window.location.pathname = 404.html

p = window.location.pathname.replace('/whatever/is/deployement/root', '')
for (var i=0; i<routes.length; i++) {
  r = routes[i]; // not using _.each because we want to break out of the loop
  if p.startsWith(r) {
    window.location.pathname = window.location.pathname.substring(0, p.length()) + r;
    window.location.anchor = p.substring(r.length(), p.length())
    break;
  }
}    
```