No longer test on Ruby 1.8
No longer test on Ruby 1.8

Ruby 1.8 won't be supported in the next version.

bfosberry/steam-condenser-ruby,kickback/steam-condenser-ruby,jpalumickas/steam-condenser-ruby,Arie/steam-condenser-ruby,koraktor/steam-condenser-ruby,hcool/steam-condenser-ruby