when I try to upload a large file, localstack basically freezes (and eventually times out).  
But if the file is all `1` bytes it succeeds.

succeeds:
```bash
aws s3 --endpoint-url=http://localhost:4572 mb s3://testbucket
python -c "print '\x01'*10000000" > testfile
echo $(ls -ahl | grep testfile)
aws s3 --endpoint-url=http://localhost:4572 cp testfile s3://testbucket/testfile
```

fails:
```bash
aws s3 --endpoint-url=http://localhost:4572 mb s3://testbucket
python -c "print 'a'*10000000" > testfile
echo $(ls -ahl | grep testfile)
aws s3 --endpoint-url=http://localhost:4572 cp testfile s3://testbucket/testfile
```
so, for me, both the file content and its size determine if this triggers or not. 
I'm using the latest version `0.9.5`
import io
import os
import ssl
import gzip
import json
import uuid
import unittest
import requests
from io import BytesIO
from six.moves.urllib.request import Request, urlopen
from localstack import config
from localstack.utils.aws import aws_stack
from localstack.utils.common import (
    short_uid, get_service_protocol, to_bytes, safe_requests, to_str, new_tmp_file, rm_rf)
TEST_BUCKET_NAME_WITH_POLICY = 'test-bucket-policy-1'
TEST_BUCKET_WITH_NOTIFICATION = 'test-bucket-notification-1'
TEST_QUEUE_FOR_BUCKET_WITH_NOTIFICATION = 'test_queue_for_bucket_notification_1'
TEST_BUCKET_WITH_VERSIONING = 'test-bucket-versioning-1'
TEST_BUCKET_NAME_2 = 'test-bucket-2'
TEST_KEY_2 = 'test-key-2'
TEST_GET_OBJECT_RANGE = 17
class PutRequest(Request):