Add an option to ScrollView to control what side of the view each of its scrollbars should be on.
Better docstrings
Fixed bar-sides and some whitespace
alias `bar_side` to (`bar_side_x`, `bar_side_y`)
Change bar_side to ReferenceListProperty

Merge https://github.com/kivy/kivy

Conflicts:
	kivy/uix/scrollview.py
Merge https://github.com/kivy/kivy

Conflicts:
	kivy/data/style.kv
Merge github.com:LogicalDash/kivy
bar_side -> bar_pos
Different way of detecting scroll type, to fit with the new way of specifying it
Merge pull request #1649 from LogicalDash/master

ScrollView scrollbars may be on the left or the top