Merge pull request #14 from tiagosiebler/#12/fixgetsign

fix(#12): fix sign error for some get requests

Merge pull request #11 from tiagosiebler/#10/sign

fix(#10): signature error for param-less non-GET requests

Merge pull request #5 from tiagosiebler/#4/urlsuffix

fix(#4): url suffix

Merge pull request #3 from tiagosiebler/ftxus

Add support for ftx.us