Snowplow Ruby Tracker v0.5.0

Makes the Tracker more robust, plus introduces several breaking API changes

• Blog post

Bug fixes

• Made synchronous flush wait until buffer is empty (#79)
• Started handling all network-related exceptions (#76)
• Started treating all 2xx and 3xx status codes as successful (#75)
• Prevented the buffer from being flushed when it is empty (#62)
• Made Emitter and AsyncEmitter thread-safe (#74)
• Fixed callback logic to only fire one callback per buffer flush (#61)

New features

• Added set_fingerprint method, thanks @kazjote! (#65)

API changes

• Made tracker.flush synchronous by default (#80)
• Added SelfDescribingJson class (#82)
• Made buffer size 1-indexed rather than 0-indexed (#67)
• Made number of worker threads used by AsyncEmitter configurable (#77)

Under the hood

• Bumped contexts schema to 1-0-1 (#53)
• Updated Contracts dependency range to "~> 0.7", "<= 0.11" (#81)
• Moved Contracts mixin inside classes (#73)

Build and documentation

• Updated Travis image to show status of master branch (#78)
• Added bundler installation to up.guidance (#83)