Fix leaderboard tiers filter with new API changes

[AkinariHex]

This PR change the tiers filter for leaderboards page accordingly to the new API change:

• Address new proposed leaderboard filter behavior otr-api#216

closes #138

[hburn7]

I don't quite understand all of the code changes. Assuming Akinari has tested thoroughly.

[AkinariHex]

I don't quite understand all of the code changes. Assuming Akinari has tested thoroughly.

The changes I made:

• remove the excluded Tiers and rename the old variables name of Ranks with tiers.
• made the checkbox to have only 2 states, selected and blank.
• fixed incorrect pushing of tiers selected in the url bar
• the website is sending to the api only the selected tiers as true value

[hburn7]

I don't quite understand all of the code changes. Assuming Akinari has tested thoroughly.

The changes I made:

* remove the excluded Tiers and rename the old variables name of `Ranks` with `tiers`.

* made the checkbox to have only 2 states, selected and blank.

* fixed incorrect pushing of tiers selected in the url bar

* the website is sending to the api only the selected tiers as `true` value

Great, thanks for the breakdown.