storage: factorize not implemented methods

There's a lot of driver that are not implementing everything, and as
time goes by, this is getting and going to be more and more common. Not
all drivers are suited to do everything, so implementing every methods
as abstract makes a lot of NotImplementedError raising redundant.

This patch makes stop using that and remove a lot of useless copy pasted
code.

Change-Id: I9e48c4f0484033061a3c3461d761e4cea4b8e75e
Merge "storage: factorize not implemented methods"