add a helper script to update github_usernames.txt file in data dir from github poc json data we have stored in our db

lib/tasks/github_usernames_populate.rb

@@ -0,0 +1,13 @@
+class GithubUsernamesPopulate
+  def self.usernames_from_pocs
+    GithubPoc.pluck(:owner).map {|h| h['login']}.sort.uniq
+  end
+
+  def self.update_file
+    fp = '/data_importer/data/github_usernames.txt'
+    File.open(fp, "w+") do |f|
+      puts "Updating username file found at #{fp}"
+      f.puts(usernames_from_pocs)
+    end
+  end
+end