added README and add pull task

Author: sideshowcoder

README.md

@@ -1,6 +1,8 @@
-# Dotenv::Heroku
+# Dotenv Heroku
 
-TODO: Write a gem description
+Support for config push and pull via Rake tasks for
+[dotenv](https://github.com/bkeepers/dotenv). The rake tasks rely on the
+`heroku` excutable to be present in the PATH.
 
 ## Installation
 
@@ -18,7 +20,30 @@ Or install it yourself as:
 
 ## Usage
 
-TODO: Write usage instructions here
+Add
+
+    require "dotenv-heroku/tasks"
+
+to your Rakefile.
+
+You can now run
+
+    $ rake config:pull
+
+to pull the current heroku config to the local .env file, you can also pass the
+desired file as an argument
+
+    $ rake config:pull\[my_current_config\]
+
+You can also push the config to heroku via
+
+    $ rake config:push
+
+to push the config from the .env file, or
+
+    $ rake config:push\[my_current_config\]
+
+to push the config from the my_current_config file
 
 ## Contributing
 

lib/dotenv-heroku/tasks.rb

@@ -1,12 +1,16 @@
 require "mkmf"
+# Make the MakeMakefile logger write file output to null.
+module MakeMakefile::Logging
+  @logfile = File::NULL
+end
 
 namespace :config do
   task :executable do
     fail "missing heroku executable from the PATH" unless find_executable "heroku"
   end
 
   desc "push the .env file to heroku config"
-  task :push, :env_file, :needs => :executable do |t, args|
+  task :push, [:env_file] => :executable do |t, args|
     args.with_defaults(env_file: ".env")
 
     File.readlines(args[:env_file]).map(&:strip).each do |value|
@@ -15,10 +19,12 @@
   end
 
   desc "pull the config from heroku and write to .env file"
-  task :pull, :env_file, :needs => :executable do |t, args|
+  task :pull, [:env_file] => :executable do |t, args|
     args.with_defaults(env_file: ".env")
 
-    remote_config = sh("heroku config").split("/n")
+    remote_config = `heroku config`
+    remote_config or fail "could not fetch remote config"
+    remote_config = remote_config.split("\n")
     remote_config.shift # remove the header
 
     # reformat the lines from