add pry and pry-debundle to the Gemfile

If you now install pry-byebug and pry-stackexplorer,
you'll get a nice debugger
Switch Faraday adapter to typhoeus

It uses curl which has less problems connecting
to a missconfigured IPv6 host (falls back to v4)
Try fetching missing parent of relayables

* Extract post fetching logic from Reshare into
  its own module
* raise proper error message when fetching fails
* raise proper error message when parent is still missing

We can't skip fetch failures or missing parents and
still need to retry them in case we're sent the parent
later on
A reshares root may be already gone when generating the notification
Discard dispatch jobs of already deleted records
Raise on 404 during Webfinger

That's at least readable, return false just causes
silly follow up errors
Fix receiving a relayable retraction through the public route
Handle already deleted photos gracefully in process photo job
Handle already deleted items gracefully in receive local batch job
bump configurate
Merge pull request #5209 from jhass/federation_improvements

Federation improvements
look for hashed version of default.css in script/server

fixes #5254
bump acts-as-taggable-on, closes #5228, #5234
Fix services in statistics.json.
Currently there is a bug in configurate that reports incorrectly the services settings if they are set as ENV variables, instead of diaspora.yml settings.
This commit works around that issue by changing the way the setting is fetched.