FEATURE: Implement check for downloaded pastes

[d-Rickyy-b]

If a downloaded paste has no content yet or was already deleted, then these checks make sure that it will be donwloaded properly or skipped.

[coveralls]

Pull Request Test Coverage Report for Build 83

• 18 of 53 (33.96%) changed or added relevant lines in 6 files are covered.
• 2 unchanged lines in 1 file lost coverage.
• Overall coverage decreased (-0.5%) to 56.884%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
pastepwn/scraping/pastebin/pastebinscraper.py	4	39	10.26%

Files with Coverage Reduction	New Missed Lines	%
pastepwn/scraping/pastebin/pastebinscraper.py	2	14.18%

Totals
Change from base Build 79:	-0.5%
Covered Lines:	690
Relevant Lines:	1213

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💛 - Coveralls