remove dependency on 'commons-httpclient:commons-httpclient:3.1' to fix java.lang.ClassCastException

```
class S3IntegrationTests extends GroovyTestCase {

    def aws

    @Test
    void getOnAMissingFileThrowsS3ServiceException() {

        // def message = shouldFail(S3ServiceException) {
            aws.s3().on('missing-bucket').get('missing-file.txt')
        // }
        // assert message == "S3 Error Message."
    }
}

```

I added a simple integration test and ran into a ClassCastException.

```
$ grails test-app
| Completed 50 unit tests, 0 failed in 908ms
| Running 1 integration test... 1 of 1
| Failure:  getOnAMissingFileThrowsS3ServiceException(grails.aws.S3IntegrationTests)
|  org.jets3t.service.S3ServiceException: Request Error: java.lang.ClassCastException: java.lang.Long cannot be cast to java.lang.Integer
	at org.jets3t.service.S3Service.getObject(S3Service.java:1379)
	at grails.plugin.aws.s3.AWSS3Tools.get(AWSS3Tools.groovy:42)
	at grails.aws.S3IntegrationTests.getOnAMissingFileThrowsS3ServiceException(S3IntegrationTests.groovy:17)
Caused by: java.lang.ClassCastException: java.lang.Long cannot be cast to java.lang.Integer
	at org.apache.http.params.AbstractHttpParams.getIntParameter(AbstractHttpParams.java:70)
	at org.apache.http.client.params.HttpClientParamConfig.getRequestConfig(HttpClientParamConfig.java:54)
	at org.apache.http.impl.client.AbstractHttpClient.doExecute(AbstractHttpClient.java:806)
	at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:82)
	at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:57)
	at org.jets3t.service.impl.rest.httpclient.RestStorageService.performRequest(RestStorageService.java:334)
	at org.jets3t.service.impl.rest.httpclient.RestStorageService.performRequest(RestStorageService.java:281)
	at org.jets3t.service.impl.rest.httpclient.RestStorageService.performRestGet(RestStorageService.java:981)
	at org.jets3t.service.impl.rest.httpclient.RestStorageService.getObjectImpl(RestStorageService.java:2150)
	at org.jets3t.service.impl.rest.httpclient.RestStorageService.getObjectImpl(RestStorageService.java:2087)
	at org.jets3t.service.StorageService.getObject(StorageService.java:1140)
	at org.jets3t.service.S3Service.getObject(S3Service.java:2583)
	at org.jets3t.service.S3Service.getObject(S3Service.java:84)
	at org.jets3t.service.StorageService.getObject(StorageService.java:525)
	at org.jets3t.service.S3Service.getObject(S3Service.java:1377)
	... 2 more
| Completed 1 integration test, 1 failed in 475ms
```