problem: proxy doesn't support long ids

fix: #48

testing/trial/src/test/groovy/io/emeraldpay/dshackle/testing/trial/proxy/MetamaskCallSpec.groovy

@@ -0,0 +1,18 @@
+package io.emeraldpay.dshackle.testing.trial.proxy
+
+import io.emeraldpay.dshackle.testing.trial.ProxyClient
+import spock.lang.Specification
+
+class MetamaskCallSpec extends Specification {
+
+    def client = ProxyClient.forPrefix("eth")
+
+    def "use long id"() {
+        when:
+        def act = client.execute(1057264140543346, "net_version", [])
+        then:
+        act.id == 1057264140543346
+        act.result != null
+        act.error == null
+    }
+}