feat(attributes): Add backfill button in flat and classbased allocation modes

Partial implementation of a "distribute points now" button for backfilling accrued Attribute points. Works with flat and classbased allocation so far; taskbased will require much fancier handling.
i18n(subscriber): replace subscriber hard-coded strings for env.t
style(tavern): add space between 2 and gems
fix(spells): temp workaround for spell & task being undefined. #2649 #2640
fix(allocateNow): Send empty object to user.ops per @colegleason suggestion

Tested with both implemented allocation modes, looks good!
Merge remote-tracking branch 'upstream/sabe/attributes' into develop
chore(cluster): remove all cluster code, just in case
`require('cluster')` is flagging issues, even if not in use. Revert this
in the near future when we can peg VersionError. @colegleason
Merge pull request #2627 from Sinza-/subscriber

i18n(subscriber): replace subscriber hard-coded strings for env.t
fix(settings): remove unnecessary code
feat(premium): backport server code for premium subs (it's just ccard
handling & uer model stuff)
chore(newrelic): add newrelic
chore(bower): strange temporary fix. Can't remember where I picked this
up, but I was having issues deploying to prod with bower referencing a
private repo (using github oauth key, see private#premium)
chore(logging): don't log in production
chore(newrelic): use license key in accordance with https://docs.newrelic.com/docs/nodejs/nodejs-agent-on-heroku
i18n(interpolation): Add string interpolation
chore(newrelic): some newrelic code location experiments
18n(merge): merge @Sinza- pr, @lefnire now it is ready
Merge branch 'develop' of https://github.com/HabitRPG/habitrpg into develop
chore(cluster): try cluster again
chore(cluster): kill & respawn pids on cluster fail, using domain-middleware