* Set logging levels in Makefile using -DRAY_COMMON_LOG_LEVEL=level
* Lower level of some LOG_ERROR messages, log the name of the table operation on failure
* Address rest of Robert's comments
* Fix spurious log message
* Merge task table and task log
* Fix test in db tests
* Address Robert's comments and some better error checking
* Add a LOG_FATAL that exits the program
* Put infrastructure in place to compute task IDs and object IDs.
* Fix version number for common library.
* Compute task IDs and object IDs deterministically.
* Address Stephanie's comments.
* Update task documentation.
* Fix formatting.
* Add more tests and checks.
* Fix formatting.
* Enable DCHECKs and change CHECKs to DCHECKs.
* Update worker code and services code to use plasma and the local scheduler.
* Cleanups.
* Fix bug in which threads were started before the worker mode was set. This caused remote functions to be defined on workers before the worker knew it was in WORKER_MODE.
* Fix bug in install-dependencies.sh.
* Lengthen timeout in failure_test.py.
* Cleanups.
* Cleanup services.start_ray_local.
* Clean up random name generation.
* Cleanups.
* Ion and Philipp's table retries
* Refactor the retry struct:
- Rename it from retry_struct to retry_info
- Retry information contains the failure callback, not the retry callback
- All functions take in retry information as an arg instead of its expanded fields
* Rename cb -> callback
* Remove prints
* Fix compiler warnings
* Change some CHECKs to greatest ASSERTs
* Key outstanding callbacks hash table with timer ID instead of callback data pointer
* Use the new retry API for table commands
* Memory cleanup in plasma unit tests
* fix Robert's comments
* add valgrind for common
