sanitize parameters before sending to socrata

If you send a parameter without a value you get
```
data:
{ code: 'query.compiler.malformed',
error: true,
message: 'Could not parse SoQL query "select * where request_date>\'2019-06-19\' and count= and district_council=\'8\' order by request_date DESC" at line 1 character 53',
data: [Object] } },
isAxiosError: true,
```

http://127.0.0.1:3000/?district_council=8&count=&time_column=request_date&url=https://information.stpaul.gov/resource/qtkm-psvs