Use source in gemlist

When `ensure => latest`, `gemlist` is called to determine the latest
available version of a gem.

If the `source` parameter is a remote gem repository, this needs to be
part of the `gem list` command run.

Fixes #128

lib/puppet/provider/rvm_gem/gem.rb

@@ -27,6 +27,9 @@ def gemlist(hash)
       command << "--local"
     else
       command << "--remote"
+      if resource[:source] && source_uri(resource[:source]).scheme =~ /^http/
+        command << '--source' << resource[:source].to_s
+      end
     end
 
     if name = hash[:justme]
@@ -76,7 +79,6 @@ def self.gemsplit(desc)
     end
   end
 
-
   def install(useversion = true)
     command = gembinary + ['install']
     command << "-v" << resource[:ensure] if (! resource[:ensure].is_a? Symbol) and useversion
@@ -89,12 +91,7 @@ def install(useversion = true)
     end
 
     if source = resource[:source]
-      begin
-        uri = URI.parse(source)
-      rescue => detail
-        fail "Invalid source '#{uri}': #{detail}"
-      end
-
+      uri = source_uri(source)
       case uri.scheme
       when nil
         # no URI scheme => interpret the source as a local file
@@ -123,6 +120,15 @@ def install(useversion = true)
     self.fail "Could not install: #{output.chomp}" if output.include?("ERROR")
   end
 
+  def source_uri(source)
+    begin
+      uri = URI.parse(source)
+    rescue => detail
+      fail "Invalid source '#{uri}': #{detail}"
+    end
+    uri
+  end
+
   def latest
     # This always gets the latest version available.
     hash = gemlist(:justme => resource[:name])