minor: fix typo in webapp config

@provider -> @webapp
Introduce eip-service-2.json to add values for obfsproxy
Make web_app serve eip-service-2.json, with obfsproxy details
Let eip-service-2.json pick obfsproxy details from vpn nodes too.

When obfsproxy is deployed alongside eip service, gateway address
will be used. If standalone, ip_address will be used.
In eip_service_2 definition, move gateways from array to hash
Remove serial and version from eip_service_2 definition
/1/configs.json list service definition files by version

Introduces configs.json which list available service definition
files by version. Feature #5704
Make webapp serve /1/configs.json, config files by versions
Make definition files available in srv/leap/webapp/config/provider