Fixes #1862, added way to see full stack trace on error situations

[ameypd]

Passed verbosity as a parameter to download function. If exception occurs in the exception block, the value of verbosity is checked and if it is not equal to the default value(0), we print the stack trace using the traceback library.

[coveralls]

Pull Request Test Coverage Report for Build 3548645049

• 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 98.189%

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Totals
Change from base Build 3525207970:	0.0%
Covered Lines:	1346
Relevant Lines:	1362

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💛 - Coveralls

[jku]

Thanks, looking forward to this: I've just been working on some example client changes and no error messages has been annoying.