Added a four features to render_crumb

Hi all!
**Four features added.**
**1.** Now, we can set each parameters individually for each crumb.
example:
```ruby
add_crumb name, link, :li_class => "my_class"
```
**2.** Not render empty html_options for tags.
example:
    in rendered output we have no tag class instead <code>class=""</code>
[issue 35 solved](https://github.com/zachinglis/crummy/issues/35)
**3.** We can set each crumb on right or left side. That parameter :right_side define it.
example: 
```ruby
add_crumb support_link, {:right_side => true, :links => "/support", :li_right_class => "pull-right hidden-phone"}
```
**4.** Also, we can use a html in a crumb name. No more results as: 
```html
<a href="\"><a style"...">...</a></a>
```
when call:
```ruby
add_crumb '<a style="...">Some text</a>'
```
but will be carefully, you are need to pass href parameter in a tag for a link.