Allow to configure the module with ENV vars

[microstudi]

Thi PR allows to configure the module using ENV vars. Also documents that in the README:

---

By default, the module is configured to read the configuration from ENV variables.

Currently, the following ENV variables are supported:

ENV variable	Description	Default value
VOCDONI_API_ENDPOINT_ENV	The environment of the Vocdoni API. Only two values are accepted: dev, stg. Read more on Vocdoni SDK Usage Environment	stg
VOCDONI_MINUTES_BEFORE_START	How many minutes should the setup be run before the election starts	10

It is also possible to configure the module using the decidim-vocdoni initializer:

Decidim::Vocdoni.configure do |config|
  config.api_endpoint_env = "stg"
  config.setup_minimum_minutes_before_start = 20
end

[codecov[bot]]

Codecov Report

Merging #63 (ad4447a) into main (487a6c0) will decrease coverage by 0.05%. The diff coverage is 87.50%.

:exclamation: Current head ad4447a differs from pull request most recent head 05c375f. Consider uploading reports for the commit 05c375f to get more accurate results

@@            Coverage Diff             @@
##             main      #63      +/-   ##
==========================================
- Coverage   92.09%   92.05%   -0.05%     
==========================================
  Files          84       84              
  Lines        1582     1585       +3     
==========================================
+ Hits         1457     1459       +2     
- Misses        125      126       +1     

Impacted Files	Coverage Δ
lib/decidim/vocdoni.rb	94.11% <80.00%> (-5.89%)	:arrow_down:
...trollers/concerns/decidim/vocdoni/has_vote_flow.rb	93.33% <100.00%> (ø)
app/forms/decidim/vocdoni/admin/setup_form.rb	100.00% <100.00%> (ø)
app/models/decidim/vocdoni/election.rb	100.00% <100.00%> (ø)

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[microstudi]

@andreslucena if you can look a this, should be quick. Spec failing is due a change in Vocdoni API it seems. We are trying to solve it in another PR (#61 )

[andreslucena]

Spec failing is due a change in Vocdoni API it seems. We are trying to solve it in another PR (#61 )

I've merged #64 that already solved the problem in the CI, can you merge with develop 🙏🏽 ? Thanks

[andreslucena]

Also, I forgot to mention that I tried it locally and it works well!!