Refactor: reduce usage of absolute paths on website

[dellagustin]

This issue is a follow up of #100 ,

See the following comments:

• Change default branch name from master -> main  innersourcecommons.org#100 (comment)
• Change default branch name from master -> main  innersourcecommons.org#100 (comment)
• Change default branch name from master -> main  innersourcecommons.org#100 (comment)

#100 will be fixed with #99, but it would be still good to revert the absolute paths to relative paths.

Issues

• Assets from _head.html loading from absolute url - 925536f - Removed absolute path usage from _head.html #102
• Logo is loading from absolute url
• Navigation links are using absolute urls
• About this site section (footer?) is using absolute url
• Services section is using absolute url

[rrrutledge]

Thanks for opening this issue, @dellagustin