when clair has network problem during updating vulnerability and failed
to update vulnerability, it will keep updating and even if type ctrl^C
can't stop the clair. This patch make clair to stop updating if type
ctrl^C.
Signed-off-by: Lei Jitang <leijitang@huawei.com>
Clair will now use a YAML configuration file instead of command line
arguments as the number of parameters grows.
Also, Clair now exposes a Boot() func that allows everyone to easily
create their own project and load dynamically their own fetchers/updaters.
