Add basic “fetching more…” to the top and bottom of the tailer view (that are hidden when you hit the end of the top or bottom).
Store the “state” of the LogLines collection in a nested model so that consumers and listen to state changes (when the end is it, etc).

Use that state for view handlers to toggle visibility of “fetching more” UI.
Fix tailing to not keep on tailing when you scroll upwards.
Improve go to top and go to bottom buttons (don’t clear the current log contents unless necessary).
Add a brief delay to fetching new log pages (to prevent awkward-to-fast flicker)
Grow the log page-size (request size) exponentially as frequent pages are fetched.
Fix extra scrollbar bug.

Does this break https://github.com/HubSpot/Singularity/commit/da7e036e79b931e05216de9f7fe57df0ec45bb1c ? (doesn’t seem to in Chrome)
Oh yeah, this might not always be a log file
Remove logging.
Merge branch 'improve-tailing' into hs_staging