integrity/m2v2: fixes for orphan chunk check.

 - use long timeout (1h) for all requests to m2v2 and m2v1
 - stop the check if a network error is encountered
 - handle more cases of chunkid starting with '/'
 - change check order: chunk referencing is checked before chunk date,
   so a referenced chunk cannot be moved to lost+found

Change-Id: I57f0c7b237fe1aa852f876e72d029f00e4aaef8e
integrity: add chunk id check + fix chunk lookup in dupli

 - the new chunk id check tries to convert chunk.id attr to binary and
   on failure replaces the attr by the filename.

 - the chunk lookup used to be achieved by searching for chunk position
   which could lead to a wrong chunk being used in duplicated contexts
   (in which several potential chunks have the same position). Now the
   chunk to be used is found by looking for a chunk with the same id or
   same hash if not found. If both failed, the old way based on
   positions is used.

Change-Id: Ib0a4cc2811a63784124f7f22a99b88fb5b6430d5
Merge changes Ib0a4cc28,I57f0c7b2

* changes:
  integrity: add chunk id check + fix chunk lookup in dupli
  integrity/m2v2: fixes for orphan chunk check.