(PDK-628) Addition of module_name question to interview

[HelenCampbell]

Adds the module_name question to the interview without disturbing generate functionality.

Also includes two cleanups:

• Renaming 'name' to 'forge_username' for clarity.
• Moves all tests formally under spec/unit/cli to spec/unit/pdk/cli.

[coveralls]

Coverage increased (+0.004%) to 92.3% when pulling 407f9fa on HelenCampbell:questionname into 9de9532 on puppetlabs:master.

[coveralls]

Coverage increased (+0.004%) to 92.3% when pulling 4118b42 on HelenCampbell:questionname into 9de9532 on puppetlabs:master.

[coveralls]

Coverage increased (+0.004%) to 92.3% when pulling a666b20 on HelenCampbell:questionname into 9de9532 on puppetlabs:master.

[DavidS]

Doesn't implement PDK-628:

david@davids:~/git/pdk$ git describe --all --long
heads/questionname-0-ga666b20
david@davids:~/git/pdk$ ./bin/pdk new module
NAME
    module - Create a new module named <module_name> using given options
[...]

[DavidS]

(although, having said that, we might want to merge this as first step, and come back later to finish implementation)

[rodjek]

I think it makes sense to split pdk-628 into two PRs (this one to modify the interview in order to accommodate the convert functionality and a follow up one that modifies the CLI functionality)

[coveralls]

Coverage increased (+0.004%) to 92.3% when pulling fc0e834 on HelenCampbell:questionname into ad600d6 on puppetlabs:master.

[DavidS]

I've successfully ran the acceptance:local tests on my machine to stand in until travis fixes their bundler issue.