Make Client.version a public field and let the user define it

[robertodauria]

Due to an oversight, there was no way to set the version field. This PR fixes that.

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This change is 

[coveralls]

Pull Request Test Coverage Report for Build 814

• 3 of 3 (100.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.01%) to 81.887%

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Totals
Change from base Build 811:	0.01%
Covered Lines:	1397
Relevant Lines:	1706

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💛 - Coveralls