Add hot key for pageUp and pageDown.
Merge branch 'howling-mad-pageup-pagedowm-hotkeys' of github.com:najor/Aloha-Editor into howling-mad

Conflicts:
	src/typing.js
Merge pull request "Add hot key for pageUp and pageDown" #1235
Correct implemenation of page up/down
Fix bug in expandBackwards/expandForwards
simplified build script
Merge pull request #1242 from cprerovsky/howling-mad-build

simplified build script
Remove obsolete args variable
Don't user normalized jumpOver() in unnormalized function
Remove unused Selections.scrollTo()
Fix caret tests
Ensure selection is in viewport when user does pageUp/pageDown
Ensure that expandBackward/expandForward returns a normalized boundary
Only allow the selection to be moved where it can be placed via a click
Wip