Handle non-ascii character in meter name

In Ceilometer, meter's name is user supplied, thus can contain non ascii
characters. This patch encode Unicode objects to UTF-8 before returning the
the meter to the client.

Change-Id: I15696b1b09286270de237084869d4a2d4418be8d
Closes-Bug: 1333177
Merge "Handle non-ascii character in meter name"