'apiKey' is one that people are likely to spell wrong in their configs
as 'apikey'. Given that there's no sanity-checking around required
config values yet, and a missing API key can cause silent failures in
some modules, be liberal in accepting spelling.
According to OpsGenie API documentation:
``If using the EU instance of Opsgenie, the URL needs to be https://api.eu.opsgenie.com for requests to be
successful.```
Rather than referencing wtc.Config, instead pass the global config
Also, look up config for the module early and pass that in sooner, to deal with fewer long paths and get rid of the
ConfigKey variable
