broken-link-checker: force follow links.
broken-link-checker: force follow links.

After 3256a2c, blc honored robots.txt thus it didn't crawl anything.
Ignore robots.txt to work around the issue.

twbs/bootstrap,nice-fungal/bootstrap,zalog/bootstrap,twbs/bootstrap,tjkohli/bootstrap,tagliala/bootstrap,bardiharborow/bootstrap,kvlsrg/bootstrap,bardiharborow/bootstrap,inway/bootstrap,peterblazejewicz/bootstrap,tagliala/bootstrap,kvlsrg/bootstrap,coliff/bootstrap,m5o/bootstrap,m5o/bootstrap,zalog/bootstrap,peterblazejewicz/bootstrap,GerHobbelt/bootstrap,gijsbotje/bootstrap,stanwmusic/bootstrap,yuyokk/bootstrap,yuyokk/bootstrap,stanwmusic/bootstrap,yuyokk/bootstrap,zalog/bootstrap,yuyokk/bootstrap,gijsbotje/bootstrap,kvlsrg/bootstrap,GerHobbelt/bootstrap,peterblazejewicz/bootstrap,GerHobbelt/bootstrap,tagliala/bootstrap,inway/bootstrap,stanwmusic/bootstrap,nice-fungal/bootstrap,gijsbotje/bootstrap,inway/bootstrap,stanwmusic/bootstrap,gijsbotje/bootstrap,tjkohli/bootstrap,bardiharborow/bootstrap,bardiharborow/bootstrap,nice-fungal/bootstrap,coliff/bootstrap