Merge pull request #64 from fabaff/pastebin

Pastebin service
make clean_session configurable
Added better reporting of failed connection attempts
Improvements to LWT handling and added clientid config parameter
Changes to lwt handling and new clientid config
s/host/hostname/
INI-file per mqtt topic (Wiki updated)
	closes #67
support srv in xform() for MQTT pub and logging
clarify srv.publish
add cron-like periodic invocation of custom functions
float interval for cron
typo
add support for TLS connections to broker
	closes #69
	closes #70
add doc for certfile/keyfile
experimental for #71
convert payload to bytearray if unicode
	closes  #73
Optional callback parameter for pushover service
add callback description
add pointer to pushover doc
Merge branch 'sigio-master'