DO NOT MERGE YET! [Fog 2.0] Remove 1.8.7 support

This is the official commit to drop Ruby 1.8.7 support from fog.

This is a backwards incompatible change (for hopefully obvious reasons)
so will be part of the next MAJOR fog release `v2.0`

Ruby 1.8.7 is no longer supported by the language developers.

Anyone needing to stay on Ruby 1.8.7 such as users of LTS distros should
remain on the `v1.x` series of fog.
Are we keeping support for 1.9.2?  It's already EOL.  I can understand keeping 1.9.3 since it's not EOL until february 2015 but 1.9.2 has been dead since July: https://www.ruby-lang.org/en/news/2014/07/01/eol-for-1-8-7-and-1-9-2/