Update WSME deps to 0.5b6

We're going to use new features and bug fixed in WSME 0.5b6 in
Ceilometer to simplify our API code, so we'll need it.

Change-Id: Ib5d787db5539542caa9915dac1faa27e2ccc617d
Merge "Update WSME deps to 0.5b6"