Ability to fetch attachments

• Added option to fetch attachments (PR #70).
• Bump googleapis to v92.0.0.

Labels are here!

1. Added a new option for searching by label. The default label is INBOX. Full list of labels can be found here: https://developers.google.com/gmail/api/guides/labels?hl=en (FR #65).
2. Output a message when not enough arguments were provided to init.js.
3. Bump googleapis version to v85.0.0.

Refresh access token

1. Exposed refresh_access_token which refreshes the access token on demand (See issue #50).
2. Using latest version of googleapis (66.0.0).

Minor update

1. Using latest version of googleapis (59.0.0).
2. Using latest version of cypress (5.1.0) in https://github.com/levz0r/gmail-tester/tree/master/examples/cypress.
3. Minor security fixes in 3rd parties libraries.
4. Organized https://github.com/levz0r/gmail-tester/tree/master/examples/cypress.

Version 1.3.0 is here!

• Fixed #33: API functions will return an array of matching messages.
• Use latest googleapis (v52.1.0).
• Cypress example is now a standalone repo.

Breaking changes to check_inbox

• PR #20: rethrow googleapis error.
• Updated documentation, README.md (Issue #18).
• Uses latest googleapis lib.
• Breaking change: check_inbox doesn't accept subject, to, from & intervals from function args anymore. Use options object instead (Issue #15).

Added option to include email bodies in check_email function

PR #8.

Added more search filters

• Messages can be filtered by sender, receiver, subject and epoch dates #4.
• Updated README.MD.