Only include necessary files in the `.gem` package

[postmodern]

Change the gemspec.yml to explicitly list the necessary files and file glob patterns, so that only necessary files are included in the .gem package. This should reduce the number of files that are installed on user's systems.

Necessary Files

• Files needed by YARD to generate documentation (ex: .yardopts, .document, README.md, etc).
• lib/ files.
• bin/ files.
• data/ files (if the gem has any, besides data/completion/*).

Example YAML

files:
  - .document
  - .yardopts
  - README.md
  - ChangeLog.md
  - COPYING.txt
  - "bin/*"
  - "lib/{**/}*.rb"
  - "data/templates/{**/}*"
  - "data/tips/*/*.txt"