Added quorum_lookup

quorum_lookup picks lookup_result_enties by following rules:
1. If there are quorum lookup_result_enties with the same
timestamp, they are the final result
2. Otherwise the final result is lookup_result_enties with
the greatest timestamp
Added parallel_lookup

It lookups an information for the key in parallel in all groups
You should use it in case of you need lookup_result_entry from
more than one group
This method allows you to get lookup_result_entries almost
simultaneously from all replicas
In fact time of work almost equals to time of the slowest group
Opposite time of work of a series of lookups equals to amount
of time of work of each lookup
Fixed code style
Reimplemented prepare_latest, parallel_lookup and  quorum_lookup

Now all this lookups have common base
Added tests for parallel_lookup and quorum_lookup
weights: increase temporal selection-only (not state) weights (multiply by 10 on each step) until they sum up into large enough number for random selection

Small state weights will be summed into quite small value,
random generator will not be able to produce a value
with enough bits of entropy. In some cases @pos below
will always be zero ending up always selecting the first node.

This simple algorithm increases all weights until they sum up
to the large enough range.
v2.25.6.5
search: when search for the state for given ID only print error if there was not state found, if we found that given server's node has to handle this ID, do not print error.
node: throw client error even when dnet_add_state() returned 0 - this means we didn't connect to ANY remote node
v2.25.6.6
dnet_add_state: adding already added address is not an error
Recovery: wrapped os.rename by try/except for catching os.rename exception.
Python: added ability to use several remotes at elliptics.Node.add_remote
cache: Don't send 2 packets as lookup reply
client: Fixed trans number in lookup's trans:cmd
tests: Added 3 more tests about lookup results
route: dnet_add_state() returns either positive number of connected nodes, or negative error

In particular if it failed to connect to any node, it returns -ECONNREFUSED
Merge pull request #497 from shaitan/master

Updates and Fixes
Merge pull request #498 from euroelessar/master

protocol: Lookup fixes and improvements
Uses checker in parallel_lookup_impl to be able to check reply_error