Post count WIP.
Updating thread metadata with traversal of posts.
Added benchmarkjs as dev dependency. Updated benchmark tests

* Added delete to benchmark tests
* Keeping track of ids upon creation benchmark to pass to deletion
  benchmark. Looking the ids up out of an array might slightly affect
  the outcome of the benchmark, but it can't be helped.
* Indexes are not being deleted, also all posts/boards/threads are not
  all deleted because we arent specifying an exact sample size for each
  benchmark test
Added Update benchmarks for boards, threads and posts
Refactored Boards with Promises

Refactored all of boards, validation and tests included, to use
promises.
Updated posts/threads to utilize promises

Updated all the functions in posts and threads to utilize promises. All
tests were also updated to be mostly promise based as well. Unnecessary
helper functions were also removed. Validation files were also updated
to use promises instead of callbacks.