Modified the `SET_URI` for the `s` per support documentation
Corrected `expected` URI values for setting properties in the unit tests.
Update README.md

Elaborate that the client library is under active development and is not ready for Production use.
Merge pull request #3 from kissmetrics/ajl/fix-property-set-uri

Modified the `SET_URI` for the `s` per support documentation
Merge branch 'master' into coverage_and_build

Conflicts:
	README.md