Plugins are now disabled at startup time unless there is some relevant
configuration in hydra.conf. This avoids hydra-notify having to do a
lot of redundant work (a lot of plugins did a lot of database queries
*before* deciding they were disabled).
Note: BitBucketStatus users will need to add 'enable_bitbucket_status
= 1' to hydra.conf.
Mutliple <githubstatus> sections are possible:
* jobs: regexp for jobs to match
* inputs: the input which corresponds to the github repo/rev whose
status we want to report. Can be repeated
* authorization: Verbatim contents of the Authorization header. See
https://developer.github.com/v3/#authentication.
