hibari >> gh33 (bad sequence on common log deleted by the scavenger):
- Refactoring hlog, hlog_common, hlog_local, and brick_ets modules:
  * Update #scav{} in brick.hrl: remove log_fun field, add type spec
    on each field
  * Reorganize hlog deletion codes in the checkpoint process
  * Add spec to some functions
  * Move count_live_bytes_in_log/1 from brick_ets module to
    gmt_hlog_common
  * Delete delete_seq/2 from brick_ets module. Add a similar function
    (but with more informative info level log) to gmt_hlog_common
    module
  * Change some of "if" expressions to "case"
  * Change some of "==" and "/=" to "=:=" and "=/=" when possible
  * Delete debug print like io:format/2

- Add more info and debug level logs
  * Add file size information to various info level logs
  * Add info level logs for local hlog creation and deletion
  * Add info and debug level logs to the checkpoint process
  * Disable ?DBG_TLOG logs in write_back functions. Will update them
    later with more helpful debug messages