Java action that depends on packages jar file fails

I have a set of Java actions packaged in a jar file that I deploy on Bluemix. All Java code is packaged in a jar file with a `lib` directory that contains dependant jar files, in particular the Cloudant client. Simple actions that do not use any dependant libraries work fine. Actions that use the Cloudant library fail with a `NoClassDefFoundError`.

## Environment details:

* Bluemix
* Build on Ubuntu 16.04

## Steps to reproduce the issue:

1. Build the code with gradle
2. Deploy on bluemix (I use `wskdeploy`)
3. Invoke the example/greeting action
4. Invoke the example/cloudant-test action

## Provide the expected results and outputs:

Result invoking `example/greeting`:

```
$ bx wsk action invoke example/greeting -b
ok: invoked /_/example/greeting with id 48d37cc2dfff42c2937cc2dfff42c2cb
{
"activationId": "48d37cc2dfff42c2937cc2dfff42c2cb",
"annotations": [
{
"key": "path",
"value": "consideratehoteliers.com_dev/example/greeting"
},
{
"key": "waitTime",
"value": 493
},
{
"key": "kind",
"value": "java"
},
{
"key": "limits",
"value": {
"logs": 10,
"memory": 256,
"timeout": 60000
}
},
{
"key": "initTime",
"value": 434
}
],
"duration": 460,
"end": 1522921174650,
"logs": [],
"name": "greeting",
"namespace": "consideratehoteliers.com_dev",
"publish": false,
"response": {
"result": {
"greeting": "Hello !"
},
"status": "success",
"success": true
},
"start": 1522921174190,
"subject": "bruno@imby.bio",
"version": "0.0.1"
}
```

## Provide the actual results and outputs:

```
$ bx wsk action invoke example/cloudant_test -b
ok: invoked /_/example/cloudant_test with id b7b7df5cbc754685b7df5cbc752685c5
{
"activationId": "b7b7df5cbc754685b7df5cbc752685c5",
"annotations": [
{
"key": "path",
"value": "consideratehoteliers.com_dev/example/cloudant_test"
},
{
"key": "waitTime",
"value": 520
},
{
"key": "kind",
"value": "java"
},
{
"key": "limits",
"value": {
"logs": 10,
"memory": 256,
"timeout": 60000
}
},
{
"key": "initTime",
"value": 420
}
],
"duration": 447,
"end": 1522851950713,
"logs": [],
"name": "cloudant_test",
"namespace": "consideratehoteliers.com_dev",
"publish": false,
"response": {
"result": {
"error": "An error has occured while invoking the action (see logs for details): java.lang.NoClassDefFoundError: com/cloudant/client/api/ClientBuilder"
},
"status": "action developer error",
"success": false
},
"start": 1522851950266,
"subject": "bruno@imby.bio",
"version": "0.0.1"
}
```

## Additional information you deem important:

See attached files that include:
- the `wskdeploy` manifest
- the `gradle` build file
- two Java classes that implement the actions mentioned above, `Hello.java` that works and `CloudantTest.java` that doesn't

[code.zip](https://github.com/apache/incubator-openwhisk-runtime-java/files/1879451/code.zip)