Add support for force removing.
Add support for force removing.

Signed-off-by: Andrea Luzzardi <442ffe3ffbfd024afcf0b7f8b108d05bca3aae43@gmail.com>

samalba/dockerclient,abronan/dockerclient,mountkin/dockerclient,yhat/go-docker,curoverse/dockerclient,ibuildthecloud/dockerclient,bajh/dockerclient,selvik/dockerclient,turtlebender/dockerclient,dnephin/dockerclient,jimmyxian/dockerclient,denverdino/dockerclient,BlueDragonX/dockerclient,appfront/go-docker,crhym3/dockerclient,flavio/dockerclient,ehazlett/dockerclient,divideandconquer/dockerclient,yp-engineering/dockerclient,donhcd/dockerclient