v0.5.0

• 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