Add custom listing and sort toggle to overview tiles

[bedroesb]

Section navigation tiles will now have following parameters:

• affiliations: Turn on filtering by affiliation (true or false)
• type: specify the tiles that are being shown by giving a page type (complimentary to custom).
• search: enable search in the tiles (true or false)
• except: , separated list of page file names which should be excluded, including the file extension.
• col: give an integer to specify the number of columns/section cards per row. Default: 2.
• sort: disable sorting of contributors by adding false. Default: true.
• custom: , separated list of page_id's if you only want to show specific pages.

These parameters are more in line with the ones of contributors. This will close #196

[bedroesb]

@ziadbkh hopefully this will serve your needs. You will be able to test this feature with using this line in the _config.yml file: remote_theme: ELIXIR-Belgium/elixir-toolkit-theme (no version)