setting up for next dev cycle
port handler improvements
clean callbacks/timeouts the smart way
first pass on making sensor tab variables private

#28
dump sensor data values on tab re-initialization

fixes #28
verify version on connect
save reboot sequence settings across instances
removing obsolete message
adding flash on connect UI, backend missing
add port handler support for non-timeout callbs
mostly working flash on connect sequence
adding missing chrome.storage implementation
cleanup, info and log messages added
updating changelog
release