Use PSR-6 caching interfce & remove desarolla2 cache

[sunspikes]

• Use PSR-6 caching interfaces
• Remove Dsarrola cache adapter and use php-cache (for functional tests)

[sunspikes]

Hi @Feijs

Can you please have a look. So basically i removed Desarrola completely and decoupled the caching part (it now depends only on PSR-6 interfaces), for functional tests I'm using the array cache from php-cache and I've started using PHP 7 typehints.

Now for v2 i think,

• Add back unit tests for throttling algorithms
• Need to enforce strict types and type hints in all places (I think nullable typehints and void types would have been better, but for this min version need to be bumped to 7.1)
• Refactor the throttling algorithms a bit to reduce duplicate code & improve the documentation a bit more

That's what i can think of now, what you think ?

[sunspikes]

Why have these been removed? I can update them to match your changes in this PR if that is the issue?

It would be awesome if you can add it back. Now all of them fails because of these new changes, i've tried to fix it but it was not good as i wanted it to be :D

@Feijs Also, thank you so much for your comments!

[sunspikes]

I will merge this to the release branch, if there is something to be addressed it can be done in a new PR.