RtJsonNumber + unit tests

[amihaiemil]

Fixes #12

[coveralls]

Pull Request Test Coverage Report for Build 16

• 18 of 26 (69.23%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+7.3%) to 40.625%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
src/main/java/com/amihaiemil/eojsonp/RtJsonNumber.java	18	26	69.23%
<!--	Total:	18	26	69.23%	-->

Totals
Change from base Build 14:	7.3%
Covered Lines:	52
Relevant Lines:	128

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💛 - Coveralls

[amihaiemil]

@rultor merge it

[rultor]

@rultor merge it

@amihaiemil OK, I'll try to merge now. You can check the progress of the merge here

[rultor]

@rultor merge it

@amihaiemil Done! FYI, the full log is here (took me 2min)