- Fix some vulnerabilities

```
Name: loofah
Version: 2.2.2
Advisory: CVE-2018-16468
Criticality: Unknown
URL: flavorjones/loofah#154
Title: Loofah XSS Vulnerability
Solution: upgrade to >= 2.2.3

Name: nokogiri
Version: 1.8.4
Advisory: CVE-2018-14404
Criticality: Unknown
URL: sparklemotion/nokogiri#1785
Title: Nokogiri gem, via libxml2, is affected by multiple vulnerabilities
Solution: upgrade to >= 1.8.5

Name: rack
Version: 2.0.5
Advisory: CVE-2018-16470
Criticality: Unknown
URL: https://groups.google.com/forum/#!topic/ruby-security-ann/Dz4sRl-ktKk
Title: Possible DoS vulnerability in Rack
Solution: upgrade to >= 2.0.6

Name: rack
Version: 2.0.5
Advisory: CVE-2018-16471
Criticality: Unknown
URL: https://groups.google.com/forum/#!topic/ruby-security-ann/NAalCee8n6o
Title: Possible XSS vulnerability in Rack
Solution: upgrade to ~> 1.6.11, >= 2.0.6
```

- Fix factory_bot issues
- Closes thoughtbot#1225