fix messed up file structure

Author: sideshowcoder

lib/dotenv-heroku.rb

@@ -0,0 +1 @@
+require "dotenv-heroku/version"

lib/dotenv/heroku.rb renamed to lib/dotenv-heroku/tasks.rb

@@ -1,8 +1,6 @@
-require "dotenv/heroku/version"
 require "mkmf"
 
 namespace :config do
-
   task :executable do
     fail "missing heroku executable from the PATH" unless find_executable "heroku"
   end