eth_getTransactionCount implementation (#91)

* Implemented eth_getTransactionCount endpoint

* Linting fixes

x/evm/types/querier.go

@@ -1,10 +1,12 @@
 package types
 
 import (
-	"github.com/ethereum/go-ethereum/common/hexutil"
 	"math/big"
+
+	"github.com/ethereum/go-ethereum/common/hexutil"
 )
 
+// QueryResProtocolVersion is response type for protocol version query
 type QueryResProtocolVersion struct {
 	Version string `json:"result"`
 }
@@ -13,6 +15,7 @@ func (q QueryResProtocolVersion) String() string {
 	return q.Version
 }
 
+// QueryResBalance is response type for balance query
 type QueryResBalance struct {
 	Balance *hexutil.Big `json:"result"`
 }
@@ -21,6 +24,7 @@ func (q QueryResBalance) String() string {
 	return q.Balance.String()
 }
 
+// QueryResBlockNumber is response type for block number query
 type QueryResBlockNumber struct {
 	Number *big.Int `json:"result"`
 }
@@ -29,6 +33,7 @@ func (q QueryResBlockNumber) String() string {
 	return q.Number.String()
 }
 
+// QueryResStorage is response type for storage query
 type QueryResStorage struct {
 	Value []byte `json:"value"`
 }
@@ -37,6 +42,7 @@ func (q QueryResStorage) String() string {
 	return string(q.Value)
 }
 
+// QueryResCode is response type for code query
 type QueryResCode struct {
 	Code []byte
 }
@@ -44,3 +50,12 @@ type QueryResCode struct {
 func (q QueryResCode) String() string {
 	return string(q.Code)
 }
+
+// QueryResNonce is response type for Nonce query
+type QueryResNonce struct {
+	Nonce uint64 `json:"result"`
+}
+
+func (q QueryResNonce) String() string {
+	return string(q.Nonce)
+}