This commit attaches the mmap-backed roaring bitmaps as storage
to the fragments. Currently snapshotting is not supported from
Pilosa so the WAL will grow indefinitely, however, it is not a
difficult change to make.
This commit adds `set()` execution to the Executor. When a set is
issued and the replication factor is greater than 1 then the
query will be forwarded to all other nodes that own the partition.
Currently there is not a way to recover from a `set()` that only
succeeds on some nodes.
This commit refactors the pilosa codebase. It makes several major
changes:
* Removes bitmap handles
* Removes dispatch/hold/transport
* Removes etcd dependency
* Adds consistent hash ring for slice placement
* Refactors parser/lexer
* Adds strong typing to PQL AST
* Flattens package hierarchy
