Allow Dataformats to export files to a local path

Exporting files

1. Place dataformat_export.php in your wwwroot
2. Run said script on CLI
3. Confirm you have one file in the "tempdir/dataformat_export" folder for each dataformat type:

   $ php dataformat_export.php

   == Using /mnt/export/moodle/master/data/temp/dataformat_export ==

   Exporting csv

   Exporting excel

   Exporting html

   Exporting json

   Exporting ods

   Exporting pdf

Downloading files (regression test)

1. Create some users
2. Navigate to Users > Accounts > Bulk user actions in Site administration
3. Select All users (X) and press Add to selection
4. Select With selected users: Download and press Go
5. Confirm you can download reports in different formats
6. Create a course
7. Enrol users in course
8. Visit course participants page
9. Select all users
10. Confirm you can download reports in different formats when using With selected users
11. Create a forum in the course
12. Add some discussions/posts
13. From the Actions menu select Export
14. Confirm you can download reports in different formats