Update rainbow to 2.2.2 and package_cloud to 0.3.04

• security: update rest-client 1.6.9 to 2.0.2 to address vulnerabilities including CVE-2015-3448 and CVE-2015-1820, which exist in rest-client < 1.7.2 #3211 (closed)
• ~"gem update": rainbow 2.2.2 or higher is required to use rubocop 0.52.1 (#3205 (closed)).

Closes #3203 (closed), #3204 (closed), #3211 (closed)