Split off useful microservices

Some parts of the application should eventually be independent microservices:

[ ] sending mails via different providers (complete seperate project)
[x] calculating plans (same project, but standalone microservice; better for scaling; maybe also as a AWS Lambda service?) (see #13)
[ ] geo location via different providers
[ ] formatting phone numbers via https://github.com/debuglevel/phonenumber-microservice
[x] maybe service discovery via consul

debuglevel / walkingdinner