Refine cursor format

[pilagod]

Fix cursor separator problem described in #10

• Parse fields in cursor to json array to get rid of separator
• Add CursorEncoder and CursorDecoder
• Deprecate Encode and Decode in favor of CursorEncoder and CursorDecoder
• Encode and CursorEncoder now both return new cursor format
• Keep forward and backward compatibility between Encode, Decode, CursorEncoder and CursorDecoder
• Add Makefile
• Update README

[coveralls]

Pull Request Test Coverage Report for Build 63

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at ?%

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Totals
Change from base Build 55:	0.0%
Covered Lines:
Relevant Lines:	0

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💛 - Coveralls