Rename `katja_metrics' and `katja_queries'

`katja_metrics' is now called `katja_writer' and `katja_queries' is
called `katja_reader'. These new names better resemble what each server
does.
Update katja_reader docs
Add support for forcing a transport
Mention transport selection in README
Clarify README a bit
Spelling
Allow setting a message transport
Expand documentation a bit
Update CHANGELOG and README
Improved and documented transport selection
README punctuation
Add katja:start/0
Remove unneeded include
Add type comments
Fix CHANGELOG
Comment out EUnit coverdata import
Update erl_opts
Merge branch 'master' into development
Fix conflict in Changelog
Fix conflict in Changelog