Add amount in btc value in trading panel

[Zkffkah]

When trading alts, most of the time, we want to input the amount in btc value. So it would be a good idea to have an input for btc value and add option to select percentage of btc value of our portfolio. And when change btc value the amount of alts should change accordingly and vise versa.
Example like this one at 3commas.

[badgerwithagun]

Closing #13 which is the same issue as this, but this one has a much more useful description 👍

[badgerwithagun]

Related: #14

[Zkffkah]

Are you working on this or a PR is welcomed?

[badgerwithagun]

PRs always welcome! See https://github.com/gruelbox/orko/wiki/Contributing

Happy to provide as much help as you need.

I'm working on getting off Heroku and onto Vultr t the moment because when the market goes crazy, a Heroku box is too slow to process all the trades and Orko's engine starts to lag, which is really dangerous. Once that's done I can start looking at other issues.

[badgerwithagun]

@all-contributors add lazrfocus for ideas

[allcontributors]

@badgerwithagun

I've updated the pull request to add @lazrfocus! 🎉