Bump version to 3.0b1.

src/oscar/__init__.py

 # Use 'alpha', 'beta', 'rc' or 'final' as the 4th element to indicate release type.
-VERSION = (3, 0, 0, 'beta')
+VERSION = (3, 0, 0, 'beta', 1)
 
 
 def get_short_version():