::Segment is too generic a namespace

[iain-bryson]

Hello,

We have a product with its own concept of Segment unrelated to Segment-the-service. In order to use this gem we've had to fork and rename ::Segment to ::SegmentIO. Would you consider making this change, or accepting a PR for the change?

[nd4p90x]

@iain-bryson Please submit a PR, we will review the request and get back to you. Thanks!