Upgrade to SnakeYAML to address CVE-2017-18640 (#3228)
Upgrade to SnakeYAML to address CVE-2017-18640 (#3228)

SnakeYAML < 1.26 is vulnerable to a Billion Laughs attack (denial of service).

* https://nvd.nist.gov/vuln/detail/CVE-2017-18640
* https://bitbucket.org/asomov/snakeyaml/issues/377

Refs FasterXML/jackson-dataformats-text#187
Refs #3223
mosoft521/dropwizard,dropwizard/dropwizard,Alexey1Gavrilov/dropwizard,mosoft521/dropwizard,dropwizard/dropwizard,micsta/dropwizard,pkwarren/dropwizard,pkwarren/dropwizard,pkwarren/dropwizard,micsta/dropwizard,micsta/dropwizard,Alexey1Gavrilov/dropwizard,phambryan/dropwizard,Alexey1Gavrilov/dropwizard,mosoft521/dropwizard,phambryan/dropwizard,dropwizard/dropwizard,phambryan/dropwizard