Default to template name for application name

This requires asking for template first and then app name,
but that seems less confusing anyway.
Strip any leading/trailing space off app name
Offer numbered template choices in 'activator new'

If there are featured seed templates show only those,
otherwise show all featured templates.
Group list-templates by featured/seed status
Better error handling on bad/missing template name

Suggest where to get a list, and suggest the featured
seed templates. Also, no stack trace.
Merge pull request #481 from typesafehub/wip/havocp-command-line-tweaks

Command line tweaks