add a cli flag 'usage'
add a cli flag 'usage'

haneric21/cfssl,codyli520/cfssl,bifurcation/cfssl,j-delaney/cfssl,thesamet/cfssl,APTy/cfssl,drcapulet/cfssl,endocode/cfssl,cloudflare/cfssl,terinjokes/cfssl,endocode/cfssl,codyli520/cfssl,gtank/cfssl,BugRoger/cfssl,APTy/cfssl,mclem/cfssl,drcapulet/cfssl,jmhodges/cfssl,dhiltgen/cfssl,haneric21/cfssl,sdgdsffdsfff/cfssl,codyli520/cfssl,letsencrypt/cfssl,rolandshoemaker/cfssl,codyli520/cfssl,gtank/cfssl,thesamet/cfssl,dhiltgen/cfssl,haneric21/cfssl,geligaoli/cfssl,mitchcapper/cfssl,gtank/cfssl,geligaoli/cfssl,drcapulet/cfssl,sfurman3/cfssl,BugRoger/cfssl,cloudflare/cfssl,terinjokes/cfssl,endocode/cfssl,letsencrypt/cfssl,geligaoli/cfssl,bifurcation/cfssl,thesamet/cfssl,mclem/cfssl,letsencrypt/cfssl,geligaoli/cfssl,wl2002/cfssl,sfurman3/cfssl,dhiltgen/cfssl,BugRoger/cfssl,rolandshoemaker/cfssl,mitchcapper/cfssl,haneric21/cfssl,wl2002/cfssl,j-delaney/cfssl,sdgdsffdsfff/cfssl,sdgdsffdsfff/cfssl,mclem/cfssl,sdgdsffdsfff/cfssl,dhiltgen/cfssl,wl2002/cfssl,sfurman3/cfssl,geligaoli/cfssl,letsencrypt/cfssl,sfurman3/cfssl,cloudflare/cfssl,bossjones/cfssl,haneric21/cfssl,jmhodges/cfssl,wl2002/cfssl,j-delaney/cfssl,sfurman3/cfssl,rolandshoemaker/cfssl,terinjokes/cfssl,mitchcapper/cfssl,jmhodges/cfssl,bossjones/cfssl,bossjones/cfssl,wl2002/cfssl,endocode/cfssl,bifurcation/cfssl,j-delaney/cfssl,rolandshoemaker/cfssl,bossjones/cfssl,APTy/cfssl,mclem/cfssl,terinjokes/cfssl,mclem/cfssl,cloudflare/cfssl,codyli520/cfssl,jmhodges/cfssl,BugRoger/cfssl,rolandshoemaker/cfssl,APTy/cfssl,thesamet/cfssl,drcapulet/cfssl,gtank/cfssl,bifurcation/cfssl,drcapulet/cfssl,j-delaney/cfssl,APTy/cfssl,endocode/cfssl,dhiltgen/cfssl