Updates documentation for SingleStat thresholds

The implementation of thresholds changed after fixing #3248. Docs
updated to reflect and explain the change.

npm for node 4 on circleci is really old. This updates npm and will
hopefully make the build green again.

Uses width set to 800px for invite div instead of position fixed. It
looks the same for desktop and makes the button clickable on smaller
resolutions and mobile. Although it is not really responsive so the
text will be small on mobiles. Better that though than a non-clickable
button.

After a refactoring the sidemenu-canvas css class disappeared so changed the code from #3741 to use the main-view class instead.

This change have caused alot of questions. So we revert

Reduce the amount of thresholds values to two in singlestat panel

closes #3248

and change to typescript

merge apiPlugins with appPlugins

Support OpenTSDB 2.2 fill policies, closes #3802

Fix dashboard sorting in playlists