Make config an array instead of multiple variables

Variables in config.php wouldn't be avaliable in my_doge_bot's
constructor due to wrong visibility. Put them into an array to
fix this issue.

Signed-off-by: Wen-chien Jesse Sung <jesse@cola.voip.idv.tw>
Import previous status if it is set in config

Import init_buy_count or init_sell_count if it is found in config.
We'll only take one and set the other to zero.

Signed-off-by: Wen-chien Jesse Sung <jesse@cola.voip.idv.tw>