Don't record and use TTP/TTR from observe

Use an exponential backoff pattern for durability polling, as the
responses from the server side can be unreliable

Change-Id: I919eb1d5262fc01747ebd4f723589c333572cf3b
Don't failout all commands on a timeout.

Only fail those commands which are old enough to have timed out already

Change-Id: I344e45d99457efcefce8b0edaecd85149e2f3083
Fixup vbmap info - don't error unless config doesn't exist

Change-Id: Ie250f5831291f6c6ff15da889dc34007aa160676
bconf_io: Close connection if lcb_connection_start fails

Change-Id: Ida9a87d06e6cc58654b8f5acd5e81dcb700f401a