ansible: add Python 3 to SmartOS hosts

[richardlau]

The inventory changes are from #2568 (so I can get the correct IP addresses to run the playbook against) and can be ignored.

Latest available Python 3 on SmartOS 17 appears to be Python 3.6.4, while on SmartOS 18 it is Python 3.7.1.

SmartOS 17:

# pkgin search python3
python36-3.6.4 =     Interpreted, interactive, object-oriented programming language
python35-3.5.4nb1    Interpreted, interactive, object-oriented programming language
python34-3.4.7nb1    Interpreted, interactive, object-oriented programming language

SmartOS 18:

# pkgin search python3
python37-3.7.1       Interpreted, interactive, object-oriented programming language
python36-3.6.7       Interpreted, interactive, object-oriented programming language
python35-3.5.6       Interpreted, interactive, object-oriented programming language
python34-3.4.9       Interpreted, interactive, object-oriented programming language

I have run these changes against:

• release-joyent-smartos17-x64-2
• release-joyent-smartos18-x64-2
• test-joyent-smartos17-x64-3
• test-joyent-smartos17-x64-4
• test-joyent-smartos18-x64-3
• test-joyent-smartos18-x64-4

[AshCripps]

LGTM with or without the inv changes