Dotenv values containing spaces must be surrounded by quotes

**Describe the bug**
Cannot start CachetHQ via docker-compose.
```
cachet_1 | + checkdbinitmysql
cachet_1 |
cachet_1 | + table=sessions
cachet_1 | ++ mysql -N -s -h 172.17.0.1 -u cachet -ppassword cachet -P 3306 -e 'select count(*) from information_schema.tables where table_schema='\''cachet'\'' and table_name='\''chq_sessions'\'';'
cachet_1 | + [[ 0 -eq 1 ]]
cachet_1 | + echo 'Table chq_sessions does not exist! ...'
cachet_1 | + init_db
cachet_1 | + echo 'Initializing Cachet database ...'
cachet_1 | Table chq_sessions does not exist! ...
cachet_1 | Initializing Cachet database ...
cachet_1 | + php artisan cachet:install --no-interaction
cachet_1 | The environment file is invalid: Dotenv values containing spaces must be surrounded by quotes.
```

**Environment**
- Ubuntu server
- `git pull` done

**Used app version**
Docker release of Cachet (v.2.4 in `docker-compose.yml` file)