Add #destroy to pipedrive/base

[natikgadzhi]

An easy way to delete items via ruby api.

No tests though. I'm using almost the same code for deals, organizations, contacts etc and it works.

I can see a situation this backfires: trying to remove a person /w associated activities on him will result in an error and we should either support force: true, or return a relevant message.

But still, returning bad_response will give sufficient information. That't a good first step, right?

[coveralls]

Coverage decreased (-0.57%) to 77.54% when pulling af2b0a3 on xnutsive:patch-1 into e640075 on GeneralScripting:master.