Remove Support for Ruby v1.8.7

[Ruby 1.8.7 is dead](https://www.ruby-lang.org/en/news/2013/06/30/we-retire-1-8-7/).

We can start pressing forward with [better hash syntax](http://stackoverflow.com/questions/11412242/what-are-the-benefits-of-the-new-hash-syntax-in-ruby-1-9)
and newer libraries which only support 1.9 and greater. Yay for The Future! (tm)