[WIP] Add custom font data types

[sbocinec]

This PR is addressing #34 and adding some of the common used font data types to the custom data file:

• font/otf
• font/woff
• font/woff2

List of changes:

• Add additional custom font types (otf,woff,woff2)
• Update data tables
• Fix video/webm subclass element

Here is how the changes behave:

[1] pry(main)> Marcel::MimeType.for Pathname.new("spec/factories/fonts/regular.ttf")
=> "font/ttf"
[2] pry(main)> Marcel::MimeType.for Pathname.new("spec/factories/fonts/regular.woff")
=> "font/woff"
[5] pry(main)> Marcel::MimeType.for Pathname.new("spec/factories/fonts/regular.otf")
=> "font/otf"
[9] pry(main)> Marcel::MimeType.for extension: "woff"
=> "font/woff"
[10] pry(main)> Marcel::MimeType.for extension: "woff2"
=> "font/woff2"
[11] pry(main)> Marcel::MimeType.for extension: "otf"  
=> "application/x-font-otf"

Other notes:

• There is a lot of ambiguity on what's the proper MIME type for the OTF https://stackoverflow.com/questions/2871655/proper-mime-type-for-otf-fonts - font/otf vs application/x-font-otf vs application/x-font-opentype 🤔
• tests are not yet updated to include example files for the newly added types