Support for LINE messaging

[mgilangjanuar]

I just made pull request #26. Please review my changes and generate API key for LINE platform in https://tracker.dashbot.io/track.

[mgilangjanuar]

This is my log for LINE platform with generic API Key.

validation error:  {"success":false,"errors":[{"message":"the supplied platform 'line' does not match the bots configured platform on dashbot."}]}
Dashbot Outgoing: https://tracker.dashbot.io/track?apiKey=[GENERIC_API_KEY]&type=outgoing&platform=line&v=9.9.2-npm

[sinned]

Thanks so much for this! We'll take a look.