Fix sentry release information

[jorg-vr]

This pull request adds release information to sentry. It also takes the environment information from rails instead of recalculating it based on hostname.

It also removes the sending of release info to sentry, as the release name is now contained in the tag. And sourcemaps are already pushed upon build.

I have also loaded sentry within frames (where it wasn't present yet).

[niknetniko]

What is the rational for guarding against missing environment/release tags? I would assume that if they are missing, this should be an error, but I can also see not wanting to break all JavaScript just because these tags are missing

[jorg-vr]

If there is an issue with the tags, 'there should be an error' indeed
But that error would result in sentry not being initiated, thus we wouldn't know the error happened.

Now those errors will be logged under 'unknown'. Seeing 'unknown' in sentry should trigger us to wonder why we didn't get the information