[Capacity] replace currency trait with fungible trait

[p5150j]

After talking speaking with Parity they are going to replace the currency trait with fungible trait.

[p5150j]

Hey team! Please add your planning poker estimate with Zenhub @enddynayn @shannonwells @johnmela

[p5150j]

Please add your planning poker estimate with Zenhub @mattheworris

[wilwade]

paritytech/substrate#12951

[shannonwells]

Chatted with @enddynayn - not all of the fungible traits that we want are in polkadot-v0.9.36, but they're in master. I have something almost working, that adds our own traits to replace them and only one compile error, but we want to wait until we're caught up with a version of substrate that includes all the traits we need. Branch is replace-currency-with-fungible-trait-#942

[shannonwells]

I think this is probably ready with the release of substrate's polkadot-v0.9.42