Add color support

You can change the default color by changing the props (.props file for
the filesystem storage backend).
Decode urls in XML (fix #26)
Merge pull request #48 from jspricke/color

Add color support
Get a random color for calendars with no color
Update news
Fix built-in owner_only right
Merge pull request #54 from osalmi/master

Fix built-in owner_only right
Merge branch 'master' of github.com:Kozea/Radicale