Added timeouts to HTTP requests.
Remove incident_key from the "Advanced" group.
Additional documentation for the various classes.
Display any HTTP error string from PagerDuty's server.
Do TAL processing before json string creation.
Merge remote-tracking branch 'origin/code_review' into fix-tal-json-mess

Conflicts:
	ZenPacks/PagerDuty/APINotification/actions.py
Merge pull request #1 from PagerDuty/fix-tal-json-mess

[RI-103] Do TAL processing before JSON string creation.