Change from robot.hear to robot.listen

[ajc308]

Please change robot.hear to robot.listen in these 4 instances: https://github.com/postlight/hubot-spotify-playlist/blob/master/src/spotify-playlist.coffee#L124-L133.

Since this is using robot.hear, when I run the bot locally (even with a different name), it responds to text matches regardless of the preceding name.

robot.hear - callback is called anytime a message's text matches
robot.respond - callback is only called for messages that are immediately preceded by the robot's name or alias

Hear vs. listen: https://github.com/github/hubot/blob/master/docs/scripting.md#hearing-and-responding

I tried to submit a PR for this myself but was denied due to permissions.

[mutewinter]

Write access granted.