Add files to pack into a dotnet templates

[jdebarochez]

In reference to issue #4

Adds:

• .template folder to specify scaffolding behaviour
  • Namespace is automatically taken from folder name
  • Build can be skipped after generation with --skipRestore option
• Nuspec file to generate the Nuget package

Tested as follow:

1. Generate the Nuget package with nuget pack .\SoftwareAteliers.AspNetCoreVueStarter.nuspec -OutputDirectory C:/LocalNugetFeed (where LocalNugetFeed is a local Nuget repository)
2. Install the package with dotnet new -i SoftwareAteliers.AspNetCoreVueStarter
3. Scaffold a test project with dotnet new vue -o MyProject

Let me know if you have any improvement or correction to naming I used.