rename reconfigService() to reconfigServiceWithBuildbotConfig

In the aim of simplifying the API for BuildbotService(),
we rename this method, so that the name is available for API of BuildbotService.

Next task is to convert more and more services of buildbot into BuildbotService, so that:
1) they can be abstracted from where they are configured
2) they can embed their checkConfig internally, and not in config.py

Signed-off-by: Pierre Tardy <pierre.tardy@intel.com>