Init git with an empty first commit

It is difficult to rewrite the root commit, so the first commit should
be empty. The template files are added in a second commit.

Fixes #8.
Fix issues in elisp gitignore

- Replace references to Skeletor with __PROJECT-NAME__
- Add .cask to ignored dirs
Add skeletor-user-organisation custom variable
Remove custom words
Do not make project constructors interactive
Bump version