fix: routing and reduce code

[hacdias]

This cleans up the code a bit and reduces it a bit:

• Use file name as file id - it won't be an issue because there can't be two different files with the same name on the same directory.
• Merges Upload and Download pages.
• Tweaks routing.
• Redirects invalid hashes to #/.

[hacdias]

Page for when you don't have an IPFS daemon running and you're on Upload pages:

[hacdias]

@fsdiogo I think it's ready for review.

[hacdias]

@fsdiogo that issue seems easy to solve: just a reactX that when URL changes, resets the files state. Could you take a look at the answers I gave you?

[hacdias]

@fsdiogo done!