Snowplow Ruby Tracker v0.3.0

Extra functionality bringing the tracker closer in functionality to the Python Tracker.

• Blog post

New functionality

• Added Subject class (#42)
• Added Emitter class (#39)
• Added POST support (#32)
• Added ability to send events asynchronously (#18)
• Added ability to disable contracts (#11)

API changes

• Made "name" an optional argument to track_screen_view (#38)
• Made all tracker methods chainable (#40)

Under the hood

• Changed default platform to "srv" (#37)
• Added logging (#41)