Added configuration options to Jobs Grid with icons portlet
Fix Caused by: java.lang.ArithmeticException: / by zero
	at jenkins.plugins.jobicon.CustomIconJobsPortlet.getRowCount(CustomIconJobsPortlet.java:62)
Fix Caused by: java.lang.NullPointerException
	at jenkins.plugins.jobicon.CustomIconJobsPortlet.getIconSize(CustomIconJobsPortlet.java:57)