fixed bug #104 - If subscribed to # and $SYS/# no $SYS/ topics gets delivered
Fixed keepalive=0 according to MQTT 3.1.1.

Closes #106.
publish logs are in debug, forward logs are in trace.

The info logs were too verbose.
Fixed typo in Docker instructions

Closes #107
Removed useless docker command in the readme.
Updated most dependencies.
Better afterEach in server test.
Added big message (5KB) test.
Merge branch 'master' of github.com:mw75/mosca into mw75-master
Added tests.
Bumped v0.18.0.