Improve test run by module as rake task

[stbnrivas]

I'd like to have modularized the test run by gobierto module. Something like:

bin/rails test:admin # which run gobierto_admin module 
bin/rails test:attachments
bin/rails test:budget
bin/rails test:calendars
bin/rails test:cms
bin/rails test:common
bin/rails test:core
bin/rails test:dashboard
bin/rails test:data
bin/rails test:export
bin/rails test:indicators
...

because this is tedious run and error prone

bin/rails test test/controller/gobierto_admin
bin/rails test test/models/gobierto_admin
bin/rails test test/systemgobierto_admin
....

I would take advantage of circle ci config.yml