Paging parameters don't work consistently on Chart methods

[rikkit]

Seeing some weird behaviour with the chart API:

• chart.getTopArtists returns 1 item if asked for 1, otherwise returns 20 items
• chart.getTopTracks returns 1 item if asked for 1, otherwise returns 10 items
• chart.getTopTags seems to always return page 1 of 50 items

Added some integration tests to track this.

[rikkit]

Fixed in c7a36350b79b504598a9dcd1659625d48d6fde89