Generate .gitignore file

[hseeberger]

[octonato]

This should be part of the archetype.
The maven one has it. Maybe missing on the npm one?

[hseeberger]

I have used Maven and I have no .gitignore file. So maybe it is not working as expected? Or maybe it is only available in a not yet released version?

[ennru]

The .gitignore, but it doesn't get added when running. Do dotfiles require something extra?

[ennru]

Found https://stackoverflow.com/questions/32580244/gitignore-file-is-not-copied-to-archetype-jar-workarounds

[ennru]

Fixed with #97