Add a flag / options for -e --err-no-data
abstract out an errNoData function & call it from appropriate places

1) if we don't receive a repsonse or it's not formatted correctly
2) if we don't receive any metrics & the --err-no-data flag is set
add more documentation in the form of command line --help
cosmetic changes to make things more uniform
Let's return a valid json array of objects
Let's move Main.hs under src/ just for fun. (works with intellij better)
version bump
update ignore file
Tiny tweaks remembered as I'm working on KIA
smaller diagram
Merge pull request #6 from Knewton/2809-error-on-no-data-flag

2809 error on no data flag