Fix memory leak

[loris]

Hi,
Noticed a memory leak when calling the sign method with an intermediate certificate.
Both intermediate and sk variables are leaking.
(I'm only using the sign method, so not sure If another leak is still in the verify method)

[coveralls]

Pull Request Test Coverage Report for Build 22

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 100.0%

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Totals
Change from base Build 21:	0.0%
Covered Lines:	65
Relevant Lines:	65

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💛 - Coveralls

[coveralls]

Pull Request Test Coverage Report for Build 22

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 100.0%

---

Totals
Change from base Build 21:	0.0%
Covered Lines:	65
Relevant Lines:	65

---

💛 - Coveralls

[loris]

FYI, memory usage on our production servers, 4cd9ccbc deploy was first usage of this package, 21912d2e deploy contains this fix.

[kobim]

Hi @loris, thanks for pointing and fixing this!
I'll go ahead and publish it as a new version in a few minutes.