direct user to download Keplr extension

[turadg]

Problem to be Solved

When someone goes to psm.inter.trade they don't get any error feedback about not having Keplr installed.

Design

if they click "Connect Keplr" and there is no window.keplr then tell user how to install it.

(#29 was a different approach but would have problems with document load timing)

[turadg]

"Nice to have" given the documentation and that users hitting this app understand Cosmos