force delete the docker container

we don't want to leave it lying around
4 gigs of ram per container on docker is the default
lets try using --dev
allow passing custom timeouts
don't break if payload.timeouts is blank
handle log_silence timeout in seconds (like build_script and hard_limit)
sauce_labs: include instance ID in the log output when booting
make the log_silence message display minutes, too
display minutes in integer format in error messages
Merge pull request #98 from travis-ci/sf-custom-timeouts

Allow passing custom timeouts
Merge branch 'master' into ha-feature-template_group_selection

Conflicts:
	lib/travis/worker/virtual_machine/blue_box.rb
Turn BLUE_BOX_VM_DEFAULTS into a method

To conform with the current master branch