encoding error should be notified at least as log.error

[Kun Huang]

https://github.com/openstack/swift/blob/master/swift/common/bufferedhttp.py#L133

if isinstance(path, unicode):
        try:
            path = path.encode("utf-8")
        except UnicodeError:
            pass # what should I do?

Before pass this error, we should log it, in error or warning level.
It'll be more dangerous when error happens and no direct origin information lives in log.
We should log here for potential debuging.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/21778

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/21778
Committed: http://github.com/openstack/swift/commit/f4a09ebf478ecb69a95c7920048b69184a7ad033
Submitter: Jenkins
Branch: master

commit f4a09ebf478ecb69a95c7920048b69184a7ad033
Author: Kun Huang <email address hidden>
Date: Tue Feb 12 21:35:53 2013 +0800

    log message in exception level when path encoding errors happen.

    Original code is kind of except-pass. This will ignore the error
    occurs in process of encoding path. And if such error happened
    without any information in logs, developer have to debug in a
    long distance from error stack. That's wasting time, so there
    should be a logging message here.

    Fixes: bug #1123048
    Change-Id: I7941b524e936241fb8d62fad5ad90de3daffe5e7