Version bump (3.0.4)
Update README
Make bundle manifests compatible with EC2

This is a backport of commits e565f32 through 8b7fae0.

Fixes TOOLS-294
Merge branch '3.0-maint' into 3.1-maint

Conflicts:
	README
	euca2ools/__init__.py
	euca2ools/commands/bundle/__init__.py
	euca2ools/commands/bundle/bundleimage.py
User account in manifest to not contain dashes

Partial fix for TOOLS-294
Reorder manifest contents for EC2 compatibility

Partial fix for TOOLS-294
Add a XML declaration to manifests

Partial fix for TOOLS-294
Don't crash when self.args['user'] is None