v0.7.5 release

Retries

• server side retry (#516)
• Sync retry IDL (#549)
• Add support for RetryPolicy in test framework (#557)
• Local retry for local activity (#553)
• Make ExpirationInterval on retry policy required. (#560)
• Retry with heartbeat details (#570)

Bug fixes

• Fix getErrorDetails panic (#542)
• Ignore result when error is not nil (#543)
• Handle cancel timer failed event (#545)
• Fail decision task when process task return error (#544)
• Singleton default data converter (#547)
• Cancel outstanding activities on DomainNotActiveError (#556)
• Skip processing more events on panic (#561)
• Fix nil pointer error when access sticky cache (#565)
• Fix test framework to allow same ActivityID from different child work
• Fix max concurrent decision task (#575)
• Flush buffered heartbeat if activity failed (#577)
• Return WorkflowAlreadyStarted error from child workflow if the start

Miscellaneous

• Add metrics for non-deterministic error. (#551)
• Update README.md (#552)
• Add WorkflowID and RunID to panic log (#554)
• Drop local activity result when it no longer apply (#555)
• Emit StickyCacheEvict metrics (#559)
• Enable signal to child workflow in test framework (#566)
• Add support for WorkflowTimeout to test framework (#567)
• Add heartbeat support on test framework (#572)
• RequestCancelActivityTaskFailedEvent is not decision event (#580)
• Migrate from using glide to dep (#581)
• Test framework: make sure start listener returns before activity star
• Add package overview documentation (#586)