[Config] Restore support for custom repos dir

lib/cocoapods/config.rb

@@ -113,7 +113,7 @@ module Pod
     # @return [Pathname] the directory where the CocoaPods sources are stored.
     #
     def repos_dir
-      @repos_dir ||= Pathname.new(ENV['HOME'] + "/.cocoapods")
+      @repos_dir ||= Pathname.new(ENV['CP_REPOS_DIR'] || "~/.cocoapods").expand_path
     end
 
     attr_writer :repos_dir
@@ -165,7 +165,7 @@ module Pod
     # @return [Pathname] The path of the file which contains the user settings.
     #
     def user_settings_file
-      Pathname.new(ENV['HOME'] + "/.cocoapods/config.yaml")
+      repos_dir + "config.yaml"
     end
 
     # Sets the values of the attributes with the given hash.

spec/unit/config_spec.rb

@@ -16,6 +16,16 @@ module Pod
       it "returns the path to the spec-repos dir" do
         config.repos_dir.should == Pathname.new("~/.cocoapods").expand_path
       end
+
+      it "returns the path to the spec-repos dir" do
+        config.repos_dir.should == Pathname.new("~/.cocoapods").expand_path
+      end
+
+      it "allows to specify the repos dir with an environment variable" do
+        ENV['CP_REPOS_DIR'] = '~/custom_repos_dir'
+        config.repos_dir.should == Pathname.new("~/custom_repos_dir").expand_path
+        ENV.delete('CP_REPOS_DIR')
+      end
     end
 
     describe "Concerning a user's project, which is expected in the current working directory" do