Various improvements

1) Added helpers #badge and #label for badges and labels (with specs & readme).
2) #glyph helper added to readme
3) Added #uri_state method returning state of passed url/path comparing to current url/path:
 ```
# Assume that current url is /blog/categories/test
uri_state('/blog/categories/test')   # :active
uri_state('/blog/categories')        # :chosen
uri_state('/blog/categories/test/3') # :inactive    
```
4) Patched navbar to use #uri_state. A navbar button is typically required to be active if user opens embedded page. For example, "Foos" ("/foos") must have .active class if user goes to "New foo" ("/foos/new").