Postal appender now uses UTF-8 charset by default
Merge branches 'master' and 'dev' of github.com:ptaoussanis/timbre into dev
Deps: Nippy 2.5.2
Fix namespace filtering (mlb-)
v3.0.0-RC3 (hotfix)
Added tests.

Note that the last two tests added should actually pass, but do not as
of version 2.7.1 of this library.