recovery: fix container creation in merge
recovery: removed unused get_address_ranges()
recovery: merge: do not fail on single error
recovery: fixed computation of recovery ranges

Now we grouping routes by grous_id's before merging.
Also added implicit insertion of min and max ids.

This greatly simplifies following code and fixes merge route
computation.
recovery: actualize comments
Merge pull request #195 from SaveTheRbtz/master

Recovery: hash-ring wrap around fix, improved robust and minor improvements