moved variable replacement into replaceVariables() function.
added test for variables from included files.
fixed and added test for variable names conflicting when they are similar e.g.: @color @color2
nom test was giving false positives, using the mocha `done` callback seems to fix it.
Changed replace method regexs to non global (`//g`), to avoid bug in replacements not working
Added test `manyVariables`
Merge pull request #5 from Ashton-W/master

variable replacement fixes and replaceVariables() function