* Basic functionality for LRU eviction.
* Test eviction.
* Factor out eviction policy.
* Move delete_object into eviction policy.
* Replace array of released objects with an LRU cache (hash table + doubly linked list).
* Finish rebase on master.
* Move actual object deletion away from eviction policy and into plasma store.
* Small fixes.
* Fixes.
* Make remove_object_from_lru_cache always remove the object.
* Minor formatting and comments.
* Pass in allowed memory as argument to Plasma store.
* Small fix.
* Remove hiredis submodule.
* Squashed 'src/common/thirdparty/hiredis/' content from commit acd1966
git-subtree-dir: src/common/thirdparty/hiredis
git-subtree-split: acd1966bf7f5e1be74b426272635c672def78779
* Make Plasma tests pass.
* Make Photon tests pass.
* Compile and test with Travis.
* Deactive fetch test so that the tests pass.
