dftech add command

[ben-edna]

Create a dfetch add command which adds a new project to the manifest. Potentially make it interactively so a user is guided.

[spoorcc]

I like the interactive that is used in carbon-now:

• We make add comment that takes in remote address
• dfetch add -i git@github.com:dfetch-org/dfetch.git
• ? Src:
• ? Dst:
• ? Name:
• ? Version:
  • branch
  • tag
  • revision

[ben-edna]