Fixes #123 - Avoid Unpermitted parameters on Playlists::SongsController

[jaredmoody]

Calling permit on the base params makes other params that are submitted invalid - and there are others, such as playlist_id and authenticity_token.

Because no params are being mass-assigned, there's no benefit to calling permit anyway, so remove playlist_songs_params

Added a config to dev and test to raise when unpermitted params are passed to surface errors like this.

[coveralls]

Pull Request Test Coverage Report for Build 1932495450

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Details

• 4 of 4 (100.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.009%) to 96.923%

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Totals
Change from base Build 1919682472:	-0.009%
Covered Lines:	693
Relevant Lines:	715

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💛 - Coveralls

[jaredmoody]

I thought this was the source of #123, but I think I was wrong - I just deployed it to my local install and the issue persists.

However, I think the patch is still worthwhile as it prevents unpermitted parameter errors, and causes future unpermitted parameters to be found in the development/test environments.