Only use buttons for submissions with reviews or comments

The rationale being that some people iteratively send in their
exercises, without awaiting comments. This makes it really hard to
judge if you're looking at submission 8 whether a whole discussion has
already been had, or whether no discussion has been had at all.
Meetup exercise for Common Lisp.
Improved styling

created proper style for deemphasized button,
also fixed styling of active submission
Merge pull request #1250 from markijbema/deemphasize-submissions-without-comments

Only use buttons for submissions with reviews or comments
Move some tests around

Testing allergic_to? make a bit more logical sense because it will be used
later to implement .list.

Also removed a couple of tests that were duplicative.
Use refute

This makes it a bit more semantic and exposes people to both assert and refute
Merge pull request #1270 from msgehard/rearrange_allergies_tests

Move some tests around
Fix timezone bug in nitstats
Add a little Unicode to bob

The idea is to make people aware that `[A-Z]` is not a good regex for checking
for letters.
Simplified the instructions for submitter/nitpicker

There are a lot of directions to the right of the submission, especially on the first submission. I tried to make this a bit cleaner.
Merge pull request #1271 from pminten/elixir-bob-russian-shouting

Add a little Unicode to bob
Merge pull request #1273 from markijbema/cleaner-instructions

Simplified the instructions for submitter/nitpicker
Do not hibernate submissions where submitter is last commenter
Specify minitest gem in test helper
go/accumulate: changed 'Allergies' to 'Accumulate', added tests
Use the right order of args in elixir list-ops reduce

The function passed to reduce should take args `element, acc`, not `acc,
element` to be consistent with `Enum.reduce`.
Merge pull request #1276 from amullins83/go_tests

go/accumulate: changed 'Allergies' to 'Accumulate', added tests
Merge pull request #1277 from pminten/elixir-list-ops-right-reduce-order

Use the right order of args in elixir list-ops reduce
Fix in nit_count update when submitter == user

The nit_count shouldn't be updated when deleting a submitter's comment.
Merge pull request #1278 from ebautistabar/update_nit_on_delete

Fix in nit_count update when submitter == user