Fix issue related to Net::IMAP.format_date change (@mnohai-mdsol)

- Bump version to 0.7.0

- Add deprecation notice of gem to readme
- Autogen Rubocop config

Version 0.6.0

Add MIT license to gemspec

tag v0.4.2

tagging v0.4.1

Version bump to 0.4.0

Version bump to 0.3.4

Version bump to 0.3.3

Regenerated gemspec for version 0.3.2