Implement eth_pendingTransactions, bump sdk version (#124)

* Update sdk version, implement pending txs, fix nonce check

* Bump cached dependencies in circleCI

* bump circleci go version

* updated linter and fixed bugs relating to go version 1.13

types/errors.go

@@ -9,11 +9,11 @@ const (
 	// DefaultCodespace reserves a Codespace for Ethermint.
 	DefaultCodespace sdk.CodespaceType = "ethermint"
 
-	CodeInvalidValue        sdk.CodeType = 1
-	CodeInvalidChainID      sdk.CodeType = 2
-	CodeInvalidSender       sdk.CodeType = 3
-	CodeVMExecution         sdk.CodeType = 4
-	CodeInvalidIntrinsicGas sdk.CodeType = 5
+	CodeInvalidValue   sdk.CodeType = 1
+	CodeInvalidChainID sdk.CodeType = 2
+	CodeInvalidSender  sdk.CodeType = 3
+	CodeVMExecution    sdk.CodeType = 4
+	CodeInvalidNonce   sdk.CodeType = 5
 )
 
 // CodeToDefaultMsg takes the CodeType variable and returns the error string
@@ -27,8 +27,8 @@ func CodeToDefaultMsg(code sdk.CodeType) string {
 		return "could not derive sender from transaction"
 	case CodeVMExecution:
 		return "error while executing evm transaction"
-	case CodeInvalidIntrinsicGas:
-		return "invalid intrinsic gas"
+	case CodeInvalidNonce:
+		return "invalid nonce"
 	default:
 		return sdk.CodeToDefaultMsg(code)
 	}
@@ -55,6 +55,6 @@ func ErrVMExecution(msg string) sdk.Error {
 }
 
 // ErrVMExecution returns a standardized SDK error resulting from an error in EVM execution.
-func ErrInvalidIntrinsicGas(msg string) sdk.Error {
-	return sdk.NewError(DefaultCodespace, CodeInvalidIntrinsicGas, msg)
+func ErrInvalidNonce(msg string) sdk.Error {
+	return sdk.NewError(DefaultCodespace, CodeInvalidNonce, msg)
 }