[async-inserts-blog] gcp upclick demo

[nellicus]

This PR adds the upclick NodeJS demo app, part of async inserts blog

[nellicus]

@gingerwizard I've added under new root folder blog-examples then async_inserts/upclick-gcp in it, as I think content starts to be not exactly tidy, of course to keep things consistent then that would involve some general reorg of existing root folders and consequent update of links in blogs though I wouldn't think it has to happen asap, so let me know if you'd rather just have a simple root async_inserts/upclick or upclick-gcp path for this PR

[gingerwizard]

@nellicus please merge