[CLEANUP] Use coin class for worker hashrate calcs
[CLEANUP] Use coin class for worker hashrate calcs

* Worker class was not using coin class for calculations
* Should improve runtime for worker status related queries

shreeneve/test,machinecoin-project/php-mpos,mmitech/php-mpos,sixxkilur/php-mpos,ychaim/php-mpos,sixxkilur/php-mpos,ychaim/php-mpos,studio666/php-mpos,xisi/php-mpos,studio666/php-mpos,bankonme/php-mpos,xisi/php-mpos,mmitech/php-mpos,ychaim/php-mpos,shreeneve/test,mmitech/php-mpos,bankonme/php-mpos,shreeneve/test,MPOS/php-mpos,studio666/php-mpos,xisi/php-mpos,sixxkilur/php-mpos,bankonme/php-mpos,machinecoin-project/php-mpos,MPOS/php-mpos,machinecoin-project/php-mpos,MPOS/php-mpos