Abstracting the request pattern.

Currently, most of the request function use the same format of http request pattern except a few.

```
headers = get_request_header()

try:
response = requests.get(url, headers=headers)
response.raise_for_status()
except requests.exceptions.HTTPError as err:
if (response.status_code in EVALAI_ERROR_CODES):
validate_token(response.json())
echo(style("Error: {}".format(response.json()["error"]), fg="red", bold=True))
else:
echo(err)
sys.exit(1)
except requests.exceptions.RequestException as err:
echo(err)
sys.exit(1)
```
This could be simplified easily by abstracting this functionality as a function.