Add data_dir command line option where scanIDs.json and logs are stored

[greenhat]

Close #196

[coveralls]

Pull Request Test Coverage Report for Build 3628713952

• 0 of 26 (0.0%) changed or added relevant lines in 4 files are covered.
• 3 unchanged lines in 1 file lost coverage.
• Overall coverage decreased (-0.3%) to 64.29%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
core/src/logging.rs	0	3	0.0%
core/src/oracle_state.rs	0	3	0.0%
core/src/main.rs	0	5	0.0%
core/src/scans.rs	0	15	0.0%
<!--	Total:	0	26	0.0%	-->

Files with Coverage Reduction	New Missed Lines	%
core/src/scans.rs	3	0%
<!--	Total:	3		-->

Totals
Change from base Build 3627716913:	-0.3%
Covered Lines:	1984
Relevant Lines:	3086

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💛 - Coveralls