Refactoring and completeness of the tests

[coveralls]

Pull Request Test Coverage Report for Build 510

• 120 of 146 (82.19%) changed or added relevant lines in 12 files are covered.
• 5 unchanged lines in 5 files lost coverage.
• Overall coverage increased (+4.4%) to 56.464%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
src/inducingpoints/greedy.jl	25	26	96.15%
src/inducingpoints/kdpp.jl	12	13	92.31%
src/inducingpoints/oips.jl	29	30	96.67%
src/inference/gibbssampling.jl	1	2	50.0%
src/prior/affinemean.jl	6	7	85.71%
src/prior/constantmean.jl	5	6	83.33%
src/prior/empiricalmean.jl	4	5	80.0%
src/prior/zeromean.jl	2	3	66.67%
src/inducingpoints/kmeans.jl	25	27	92.59%
src/inference/hmcsampling.jl	8	14	57.14%
<!--	Total:	120	146	82.19%	-->

Files with Coverage Reduction	New Missed Lines	%
src/inference/analytic.jl	1	93.75%
src/inference/analyticVI.jl	1	79.07%
src/inference/inference.jl	1	87.18%
src/inference/numericalVI.jl	1	97.44%
src/likelihood/gaussian.jl	1	90.0%
<!--	Total:	5		-->

Totals
Change from base Build 506:	4.4%
Covered Lines:	1284
Relevant Lines:	2274

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💛 - Coveralls