fix: sponsor prospectus link
Merge pull request #59 from AdrienGiboire/master

feature: add jetbrains as supporter
feature: add John Hughes as a speaker
Merge pull request #61 from polyconf/feat/john-hughes

feature: add John Hughes as a speaker
feature: add Pragmatic Bookshelf as a supporter
fix: tretton37 name
fix: tretton37
improv: MostlyErlang as media partner
fix: links color in modals
fix: M. Taszycki description, styling
feature: add selleo in bronze partners