Filename localization

Added a couple lines to the test demonstrating the problem people are having (Issue #1015 and http://forum.middlemanapp.com/t/i18n-problem-filename-lang-html-erb-does-not-work/977). Now the tests check for the extra files being spit out by middleman. 

I'm pretty new to cucumber, so feel free to give pointers, criticize, and yell at me!