bittrex APIKEY_INVALID handling

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cryptopia allows limit orders only ccxt#960

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updated addresses

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case-insensitive regex for title parsing upon receiving html errors

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removed the 256 symbols limitations from btce clones

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truncate fix ccxt#917

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python orderbook parsing workaround for none values (kuna)

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skip kuna temporarily on Travis

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python safe orderbook parsing

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Update README.md

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