jira: Implement outgoing request throttling
jira: Implement outgoing request throttling

From now on there can be only 10 pending API calls at any given time.
This can be of course overwritten to set up a custom limit, but 10 is
the default value.

Change-Id: c14677e199
Story-Id: SF-111

salsaflow/salsaflow,salsaflow/salsaflow