Add support for a way to ignore files

[brikis98]

boilerplate should support some way of specifying files in the template-folder to ignore while generating. Some of the ways ignores could be specified include:

• A new top-level section in boilerplate.yml called ignores. Example:

  variables:
  - name: Title
  - name: Description
  
  ignores:
  - .git
  - foo/bar/*
  - *.foo

• A --ignore flag that can be specified one or more times on the command-line. Example:

  boilerplate --template-folder /templates --output-folder /output --ignore '.git' --ignore 'foo/bar/*'

[josh-padnick]

My mind went to a .boilerplateignore file that has the same syntax as .gitignore, but I dislike having more than one file beyond boilerplate.yml, so the first option you suggested looks good.

[brikis98]

Agreed. That said, a --ignore command line flag could be useful too, as sometimes, you may not want to tweak the entire template for a single use case.

[yorinasub17]

This is implemented now with the skip_files config.