Aim

- Add missing init file for aim.artifacts.proto (mike1808)

- Make epoch property optional for Metric (gorarakelyan)

- Serialize and store `Metric` records using protobuf and aimrecords (gorarakelyan)
- Create RecordWriter factory which handles artifact records saving (gorarakelyan)
- Extract artifact serialization to ArtifactWriter (mike1808)

- Alert prerequisites installation message for running board (gorarakelyan)

- Update profiler interface for keras (gorarakelyan)

- Add board pull command (gorarakelyan)
- Change board ports to 43800,1,2 (gorarakelyan)
- Add ability to profile graph output nodes (gorarakelyan)
- Remove issue with autograd inside while loop (gorarakelyan)
- Add aim board development mode (gorarakelyan)
- Update board name hash algorithm to md5 (gorarakelyan)
- Add board CLI commands: up, down and upgrade (gorarakelyan)
- Add ability to tag version as a release candidate (gorarakelyan)