better error for unknown region - fixes #1983
fail gracefully when region unknown - fixes #1983
revert eof
Merge pull request #2041 from ralfharing/develop

Better error output for unknown region - fixes #1983, #2041.
check for invalid regions
Merge pull request #2107 from ralfharing/develop

check for invalid regions
Add support for request intervals in health checks.
Merge remote-tracking branch 'mattdeboard/route53-fast-healthcheck' into develop
Fixes #2109.