perf(infiniteScroll): Use isolate scope

- Change to use isolate scope with & binding
Allow to add custom CSS class to popup
[Bug] Default value overwrites the option's value.
Added unit test
Update platform.js

This is returning a number rather than a string. Not sure if the doc or the code is incorrect. To return a String you'd need to return device().v instead of device().version.
Adding sass variables for footer, subfooter and subheader heights
Allowing to footers and subheader with diferent height.

FIX #2334
adding tests for both subheaders and subfooters
Update popover.js

Hi, just added an example for the .fromTemplate() method in the docs
Using $button-border-radius on button-bar buttons
fix(tabs): slide box within modal within tabs
feat(tabs): add active color state
feat($ionicLoading): allow options.hideOnStateChange

Closes #2676
test(): remove ddescribe
refactor(backButton): update activated state
Merge pull request #2669 from kevnk/patch-1

style(): use $button-border-radius on button-bar buttons
Merge branch 'variable-subheader-height' of https://github.com/arturokunder/ionic into arturokunder-variable-subheader-height
Merge branch 'arturokunder-variable-subheader-height'
style(): set $bar-height to $bar-subheader-height
Merge branch 'master' of https://github.com/driftyco/ionic
Merge pull request #2608 from pauljandrew/patch-1

docs(platform): version is a number