Blogger - Fix Drafts

It was raising 'Original URL is missing' errors on import.

Drafts don't have published urls, so instead I created the filename from the publish date and title if the title was available.

Problematic entry:
```xml
<entry>
	<id>tag:blogger.com,1999:blog-6023422566872935933.post-1811460454476739098</id>
	<published>2012-07-03T17:57:00.001-07:00</published>
	<updated>2012-07-03T17:57:59.106-07:00</updated>
	<app:control xmlns:app='http://purl.org/atom/app#'>
		<app:draft>yes</app:draft>
	</app:control>
	<category scheme='http://schemas.google.com/g/2005#kind' term='http://schemas.google.com/blogger/2008/kind#post'/>

	<title type='text'>Quotes</title>
	<content type='html'>lorem ipsum</content>
	<link rel='edit' type='application/atom+xml' href='https://www.blogger.com/feeds/6023422566872935933/posts/default/1811460454476739098'/>
	<link rel='self' type='application/atom+xml' href='https://www.blogger.com/feeds/6023422566872935933/posts/default/1811460454476739098'/>
	<author>
		<name>anon</name>
		<uri>http://www.blogger.com/profile/03857803135896707879</uri>
		<email>noreply@blogger.com</email>
		<gd:image rel='http://schemas.google.com/g/2005#thumbnail' width='21' height='32' src='http://3.bp.blogspot.com/-fr0Nvhbd1yk/U7cYo4ppo8a/AAAAAAAAAhw/_asrpo2Pi07/s221/Yoga_002.jpg'/>
	</author>
	<thr:total>0</thr:total>
</entry>
```