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# Type of request: This is a ...

[x] bug report
[ ] feature request

# Detailed description

Localstack docker run command contains `-p 8080:8080` twice, which results in an error. When running the following command manually, I can successfully run Localstack:

```
docker run -it -e LOCALSTACK_HOSTNAME="localhost" -e TEST_AWS_ACCOUNT_ID="000000000000" -e DEFAULT_REGION="us-east-1" \
-p 443:443 \
-p 4566:4566 \
-p 8081:8081 \
-p 4567-4617:4567-4617 \
-p 8080:8080  \
--rm --privileged --name localstack_main \
-v "/private/var/folders/01/wnz8g_c95fx81w85tpl2dx300000gn/T/localstack:/tmp/localstack" -v "/var/run/docker.sock:/var/run/docker.sock" -e DOCKER_HOST="unix:///var/run/docker.sock" -e HOST_TMP_FOLDER="/private/var/folders/01/wnz8g_c95fx81w85tpl2dx300000gn/T/localstack" "localstack/localstack"
```

**OS:** MacOS Mojave 10.14.6
**Docker version:** Docker version 19.03.8, build afacb8b

## Expected behavior

Running `localstack start` should set up the stack as expected.

## Actual behavior

Running `localstack start` results in the following Docker error:
```
docker: Error response from daemon: Ports are not available: /forwards/expose/port returned unexpected status: 500.
ERRO[0000] error waiting for container: context canceled
```

# Steps to reproduce
1. Install Localstack - `pip install localstack`
2. Run Localstack - `localstack start`
3. Error is displayed

## Command used to start LocalStack
`localstack start`

## Client code (AWS SDK code snippet, or sequence of "awslocal" commands)
N/A

bootstrap_installation()
    from localstack.services import infra
    return infra.start_infra()
def start_infra_in_docker():
    container_name = MAIN_CONTAINER_NAME
    if docker_container_running(container_name):
        raise Exception('LocalStack container named "%s" is already running' % container_name)
    os.environ[ENV_SCRIPT_STARTING_DOCKER] = '1'
    
    plugin_configs = load_plugins()
    
    canonicalize_api_names()
    services = os.environ.get('SERVICES', '')
    entrypoint = os.environ.get('ENTRYPOINT', '')
    cmd = os.environ.get('CMD', '')
    user_flags = config.DOCKER_FLAGS
    image_name = os.environ.get('IMAGE_NAME', constants.DOCKER_IMAGE_NAME)
    service_ports = config.SERVICE_PORTS
    force_noninteractive = os.environ.get('FORCE_NONINTERACTIVE', '')
    
    plugin_run_params = ' '.join([
        entry.get('docker', {}).get('run_flags', '') for entry in plugin_configs])
    
    regex = r'.*-p\s+([0-9]+)(\-([0-9]+))?:([0-9]+)(\-[0-9]+)?.*'
    match = re.match(regex, user_flags)
    start = end = 0
    if match:
        start = int(match.group(1))
        end = int(match.group(3) or match.group(1))
    def is_mapped(start_port, end_port=None):