Update fitbitsleeplogs summaries

[pranavanba]

Major Changes

1. In scripts/process-data/fitbitsleeplogs.R, order LogId by StartDate before calculating NumAwakenings
   • Before we exclude the first and/or last records for each sleep episode (LogId) (when the first and/or last record for a LogId has Value==wake or Value==awake), we need to first order the records for each LogId according to StartDate, since the StartDate values within each LogId are not always ordered

Minor Changes

1. Explicitly set .groups = "keep" in summarise() to enforce that previously set groupings are used