fixed error in ECKey.getExportedPrivateKey
added test to ECKey.getExportedPrivateKey
found error in ECKey.getExportedPrivateKey - it returns uncompressed priv, even when imported priv is compressed
added test for creating new key, saving priv, checking public address, reimporting
if compressByDefault was changed to true, it breaks
fixed ECKey.getExportedPrivateKey returning uncompressed key when importing compressed