ultipro_google: support additional deduction section formats

[jktomer]

Some of my Google pay statements have a slightly different format for the deductions section than the ones supported here; they include both Based-On and Pre-Tax (yes/no) columns.

Also I happen to have exactly one pay statement with an empty document ID; included a small patch so that such a document doesn't cause an exception.

[coveralls]

Pull Request Test Coverage Report for Build 34

• 0 of 5 (0.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.05%) to 63.42%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
beancount_import/source/ultipro_google_statement.py	0	5	0.0%

Totals
Change from base Build 33:	-0.05%
Covered Lines:	4022
Relevant Lines:	6219

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💛 - Coveralls