Merge tag '1.1.0' into develop

Release 1.1.0
refactor pixel density handling per #1
support explicit retina '@2x' images, related to #1
more complete and consistent retina support, related to #1
update tests to reflect pixel ratio changes
update changelog
Merge branch 'feature/retina-pointer-position' into develop
bump to pre
typo in version
Refactor Popover class, better retina support
Merge branch 'feature/popover-refactor' into develop
bring down default font sizes for popover
prep for 1.1.1 release
Merge branch 'release/1.1.1'

Fixes #1