Add missing finance CorDapp depdendency to example code (#1413)

The example code uses cash flows and contracts, but doesn't depend on the finance CorDapp. This happens to work at the moment but should be corrected anyway.

docs/source/example-code/build.gradle

@@ -42,6 +42,9 @@ dependencies {
 
     cordaCompile project(path: ":node:capsule", configuration: 'runtimeArtifacts')
     cordaCompile project(path: ":webserver:webcapsule", configuration: 'runtimeArtifacts')
+
+    // Corda Plugins: dependent flows and services
+    cordapp project(':finance')
 }
 
 mainClassName = "net.corda.docs.ClientRpcTutorialKt"