Automatically refresh API tokens in pipe common

[tcibinan]

Relates #3583.

Adds support for refreshable API tokens to pipe common. Additionally, it updates grid engine autoscaler and user synchronisation to use the new functionality.

from pipeline.api.api import PipelineAPI
from pipeline.api.token import StaticToken, RefreshingToken

# using a static token which will eventually expire
api = PipelineAPI()
api = PipelineAPI(token=StaticToken())

# using a refreshing token which will automatically update itself
api = PipelineAPI(token=RefreshingToken())