Revert "Revert "TheWeatherCompany/grid-api#813""

This reverts commit d41e8fcccb8cd9c1414796294c40a474dbcb7dcf.
TheWeatherCompany/grid-api#813 methods implementation
ref #813 code style fix
Merge pull request #101 from TheWeatherCompany/issue-813

Add support to add/remove subnets from a load balancer.