* Implement actor field for tasks
* Implement actor management in local scheduler.
* initial python frontend for actors
* import actors on worker
* IPython code completion and tests
* prepare creating actors through local schedulers
* add actor id to PyTask
* submit actor calls to local scheduler
* starting to integrate
* simple fix
* Fixes from rebasing.
* more work on python actors
* Improve local scheduler actor handlers.
* Pass actor ID to local scheduler when connecting a client.
* first working version of actors
* fixing actors
* fix creating two copies of the same actor
* fix actors
* remove sleep
* get rid of export synchronization
* update
* insert actor methods into the queue in the right order
* remove print statements
* make it compile again after rebase
* Minor updates.
* fix python actor ids
* Pass actor_id to start_worker.
* add test
* Minor changes.
* Update actor tests.
* Temporary plan for import counter.
* Temporarily fix import counters.
* Fix some tests.
* Fixes.
* Make actor creation non-blocking.
* Fix test?
* Fix actors on Python 2.
* fix rare case.
* Fix python 2 test.
* More tests.
* Small fixes.
* Linting.
* Revert tensorflow version to 0.12.0 temporarily.
* Small fix.
* Enhance inheritance test.
* attribute-based heterogeneity-awareness in global scheduler and photon
* minor post-rebase fix
* photon: enforce dynamic capacity constraint on task dispatch
* globalsched: cap the number of times we try to schedule a task in round robin
* propagating ability to specify resource capacity to ray.init
* adding resources to remote function export and fetch/register
* globalsched: remove unused functions; update cached photon resource capacity (until next photon heartbeat)
* Add some integration tests.
* globalsched: cleanup + factor out constraint checking
* lots of style
* task_spec_required_resource: global refactor
* clang format
* clang format + comment update in photon
* clang format photon comment
* valgrind
* reduce verbosity for Travis
* Add test for scheduler load balancing.
* addressing comments
* refactoring global scheduler algorithm
* Minor cleanups.
* Linting.
* Fix array_test.py and linting.
* valgrind fix for photon tests
* Attempt to fix stress tests.
* fix hashmap free
* fix hashmap free comment
* memset photon resource vectors to 0 in case they get used before the first heartbeat
* More whitespace changes.
* Undo whitespace error I introduced.
* Split local scheduler task queue into waiting and dispatch queue
* Fix memory leak
* Add a new task scheduling status for when a task has been queued locally
* Fix global scheduler test case and add task status doc
* Documentation
* Address Philipp's comments
* Move tasks back to the waiting queue if their dependencies become unavailable
* Update existing task table entries instead of overwriting
