Merge PR #1358: Fix typos and gofmt files

* Fix typos
* gofmt -s files
* Add mispellings and gofmt checks to circle CI
* circleci: Install misspell in the linting step

types/errors.go

@@ -77,7 +77,7 @@ func CodeToDefaultMsg(code CodeType) string {
 	case CodeUnauthorized:
 		return "unauthorized"
 	case CodeInsufficientFunds:
-		return "insufficent funds"
+		return "insufficient funds"
 	case CodeUnknownRequest:
 		return "unknown request"
 	case CodeInvalidAddress:

types/gas.go

@@ -1,7 +1,5 @@
 package types
 
-import ()
-
 // Gas measured by the SDK
 type Gas = int64