Allow http interface to handles mutations

[obad2015]

Summary; the current HTTP interface is hardcoded to only handle Queries, I changed it so it would also handle mutations

[coveralls]

Pull Request Test Coverage Report for Build 1127

• 4 of 6 (66.67%) changed or added relevant lines in 1 file are covered.
• 1 unchanged line in 1 file lost coverage.
• Overall coverage increased (+0.04%) to 65.602%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
graphql/http.go	4	6	66.67%

Files with Coverage Reduction	New Missed Lines	%
reactive/graph.go	1	94.07%

Totals
Change from base Build 1112:	0.04%
Covered Lines:	3471
Relevant Lines:	5291

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💛 - Coveralls

[stephen]

thank you