Created by: bardiharborow
Bootstrap informally supports the last two LTS releases and the current release of Node. v7 is in maintenance-only mode and v8 (the current release) will begin LTS in October 2017, so this PR moves testing from v7 to v8. v4 is in maintenance-only mode, but is currently being retained for legacy support (as one of the last two LTS releases). Bootstrap's v4 support will likely be deprecated in October 2017. See https://github.com/nodejs/LTS for more information.