fix: Allow # and @ in api param names

[GentileFulvio]

I'll be honest not sure if you want this to be fixes but I had this issue mentioned here apidoc/apidoc#899 that I can't use #'s in my param names. So I guess this fixes that.

There is still a failing test also mentioned in the issue linked. Didn't want to touch it though because it's not really part of this commit/issue as this commit fixes a specific issue (The test was already broken before I added any changes). I added a new test files that explicitly tests the api_param parser instead which seemed easier than the other tests you already have in the project. Let me know what you think.

Perhaps I should include other characters as well as mentioned in the following issues. #3 #64 #66

[NicolasCARPi]

Hello,

Thanks!

I think it would be nice to include other characters too.

[GentileFulvio]

Could you provide a list of characters that should be accepted ?

['#','@', ...] ?

[NicolasCARPi]

The . too I believe.

[GentileFulvio]

Added the @ added a test for the . as well apparently that should already work.

[NicolasCARPi]

Yes in fact the . is already used for array-like params.

[NicolasCARPi]

Thanks for your contribution!