Pass init kwargs to init_app

[martincpt]

I noticed that __init__'s kwargs are currently unused while init_app could use for additional configurations which could added upon object initialization in case an app or blueprint instance added along with them.

Also I removed that old commented super call.

Closes #116

[StellaContrail]

@martincpt Your pull request seems to address the open issue #116. Perhaps it would be nice to link to the issue?

I would also like this pull request to be merged into the master branch.

[martincpt]

@StellaContrail would you like me to add a 'Closes' or 'Releated to' link?

[StellaContrail]

Thank you for your reply. I think 'Close' would be nice.