Escape URI params correctly

Hi,

I fixed problem with escaping InfluxDB queries. For example part of query with /.+/ has a escaping problem because URI.encode doesn't escape `+` sign (FYI: URI.encode has been [deprecated](https://github.com/ruby/ruby/commit/238b979f1789f95262a267d8df6239806f2859cc) in 1.9.3).

Can anyone check PR, merge it and provide new gem?

Thanks