add time_zone configutation to users

[antopalidi]

Adds configurable timezone for users in order to make Decidim more usable for multi-zone organizations/countries

fixes #10

[antopalidi]

[microstudi]

Hi @antopalidi
this is an initial review, but you can already apply (some) of the changes. I'll fully test it later and give you more feedbacks and hints on how to proceed with tests

[microstudi]

Hi @antopalidi
It seems that default values on the account_form.rb cannot extract data from the context, instead we can add the default value in the view (as suggested in the comments).
Also, it is not necessary to enforce the presence of a timezone to the user, we will just use the organization if not present.

We also need to add a test case in the file decidim-core/spec/controllers/concerns/use_organization_time_zone_spec.rb and add a case for when the time zone is defined by the user and see that it takes precedence over the organizaion (only if present)

[microstudi]

Almost there!
If left a comment, please check it out.

On the other hand, we need to look at the failing tests, the first one is about linting the YAML locale file, this can be done automatically by executing:

bundle exec i18n-tasks normalize --locales en

The second one is because (I think) you need to add

let(:timezone) { "UTC" }

at the same level of the let(:data) in the file update_account_spec.rb

[microstudi]

This is fantastic @antopalidi !
I've added an additional test, but that's it!
ready to deploy!