Add json config + parsing

Close #1
Add webserver listening on config port

Close issue #2
Centralize struct in a single file + clean

- Use logging system
- Use nicely formatted json (starting with a lowercase char)
Write ParsePushEvent + test

Close issue #7
Add logging levels

Close issue #8
Add http routing for PushEvent

Close issue #3
- Add project matching after pushevent has been parsed
Add git pull command on project update

Close #4