Silence exceptions from qpid connection.close() (from oslo)

This is commit 15d8d698b7 in oslo-incubator.

Fixes bug 1185465

Don't log exceptions that happen during connection.close().  They're
not surprising (a closed socket can't be read or written), don't
require sysadmin attention, and provide red herrings in the logs
to distract from finding real root causes of problems.

Change-Id: Ia0e25fbc11094b5ad5d6d2cf7d0e786acb3df1f6
(cherry picked from commit 361d116d820939207a0b01399c3ce50c7bc30dcd)
Merge "Silence exceptions from qpid connection.close() (from oslo)" into stable/grizzly