Framework support missing

[tomasz-czyzak]

There is an issue when your database is delivered thru framework.
During migration method:
- (BOOL)loadMetadata:(NSError **)error {
calls:
[bundles addObject:[NSBundle mainBundle]];
as a result it can't find model delivered in framework bundle and migration fails.
It should use:
[[NSBundle bundleForClass:[self class]]
or
[NSBundle bundleWithIdentifier:modelBundleIdentifier];
where modelBundleIdentifier is being passed from application thru options dictionary

[lolgear]

@tomasz-czyzak does PR #268 fix it?

[tomasz-czyzak]

Looks ok however I didn't check it. This solution is based on passing whole bundle during init.
While my private fix is based on passing only bundle id in options.
Here is my private fix: #286