Add a way to specify giter8 properties

[tgodzik]

Is your feature request related to a problem? Please describe.

The 0.9.1 release introduced the new project provider, which allows for people to reuse exitsting giter8 templates, but it doesn't allow for interactively specifying any properties as described in http://www.foundweekends.org/giter8/template.html#default.properties. It will only use the default ones.

Describe the solution you'd like
Add an option to forward the properties from Metals to the giter8 commandline tool.

Describe alternatives you've considered
Use only the default values.

Search terms:
giter8 template new project