Collector endpoint for POST
Collector endpoint for POST

- Fixes #48

iamjason/snowplow-objc-tracker,snowplow/snowplow-objc-tracker,redengineer/snowplow-objc-tracker,iamjason/snowplow-objc-tracker,snowplow/snowplow-objc-tracker,chunkyguy/snowplow-objc-tracker,iamjason/snowplow-objc-tracker,snowplow/snowplow-objc-tracker,snowplow/snowplow-objc-tracker,redengineer/snowplow-objc-tracker,chunkyguy/snowplow-objc-tracker