Cruzdb Zlog Versions Save

The first release in a serious effort to move towards a v1.0.0 release. This version focused on code simplification and stability. In particular, this release contains a simplified async I/O implementation, single-writer only (i.e. no sequencer), simplified stripe and view handling, and a reworked Ceph storage backend.

• updated and fixed the C api
• created cli action to dump log metadata
• added a backend wrapper to manage log metadata
• create view reader to manage log playback
• allow latest view to be read directly (no scanning required)
• avoid spinning when waiting for new views

• separate view and epoch-versioned-view abstractions
• use a scalable view / objectmap implementation
• moved away from protocol buffers to use only flatbuffers
• implemented a large set of unit test coverage for views
• initialize first stripe for new logs

• be/ceph: added support for controlling omap vs bytestream storage
• be/ceph: remove protocol buffers dependency from cls_zlog
• cli: basic cli infrastructure added
• be/lmdb: store unique id in the database to avoid duplicate ids
• be/bench: added simple direct backend benchmark / workload generator
• zlog clients are now registered as a rados application with ceph backend
• switched to the apache 2.0 license
• garbage collection for trimming