Revert "Require startingheight >= 230000"

This reverts commit e4330f9be4195c92cf74bba1e67583f0901b5e9b.
Check for required block height in IsGood to ensure nodes not meeting the requirement are indexed properly
Update required height to 230k
Merge pull request #8 from luke-jr/bugfix_lowheight

Include low-height nodes in dnsseed.dump