Modify Transaction::commit to use isc_commit_transaction

[dancingbug]

See #57

[coveralls]

Pull Request Test Coverage Report for Build 264721917

• 0 of 4 (100.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-32.6%) to 44.306%

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Totals
Change from base Build 254178958:	-32.6%
Covered Lines:	1241
Relevant Lines:	2801

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💛 - Coveralls

[coveralls]

Pull Request Test Coverage Report for Build 264721917

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

• For more information on this, see Tracking coverage changes with pull request builds.
• To avoid this issue with future PRs, see these Recommended CI Configurations.
• For a quick fix, rebase this PR at GitHub. Your next report should be accurate.

Details

• 7 of 8 (87.5%) changed or added relevant lines in 1 file are covered.
• 37 unchanged lines in 1 file lost coverage.
• Overall coverage increased (+0.1%) to 77.047%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
src/transaction.rs	7	8	87.5%
<!--	Total:	7	8	87.5%	-->

Files with Coverage Reduction	New Missed Lines	%
src/transaction.rs	37	45.78%
<!--	Total:	37		-->

Totals
Change from base Build 254178958:	0.1%
Covered Lines:	2145
Relevant Lines:	2784

---

💛 - Coveralls