Add logging-threshold-fixture and suppress-logging to readme
Add with-tags, tags-msg to add a tag set to :tags

Adds the with-tags macro to set tags for a scope.  The tags-msg
middleware is used to add the tags onto the :tags message key.

The :tags are not logged (by default).

Closes #2
Use the latest release of lein-pallet-release
Updated project.clj, release notes and readme for 0.1.2
Updated version for next release cycle
Add async-channel appender and memory-sink

Add an appender that writes to a core.async channel.  The memory-sink
can be used to read the channel into an atom with bounded memory usage.

Closes #3
Add :kws option to async-appender

Allow specification of the keys to forward using the :kws key. Defaults
to [:hostname :ns :args :throwable :profile-stats].