* fixed a number of cases where misaligned data was causing panics on armv7 (but not armv8)
* travis: enable arm64
* test: reduce compressed data sizes when running on arm
* arm: wait longer for snapshots
* Add test engine to manage snapshot verification testing
Test engine manages the test and metadata repositories, snapshot
checker, metadata storage persistence, and file writer. It is
the high level helper that will be invoked in the snapshot
verification testing suite.
- modify data directory file structure
- issue snapshot/restore/delete to the data directory
- accumulate metadata over the course of the test suite
- flush accumulated metadata to the metadata repository
- load historical metadata from the repository on initialization
- perform automatic data integrity verification on snap restore
This change corresponds to the robustness execution engine component from the design documentation.