add sass mixin and animation function for placeholders
run grunt test
resolve merge conflict in screens
Merge pull request #636 from optimizely/dfoxpowell/anim-placeholder-icons

add sass mixin and animation function for placeholders
fix sass mixin for case of only one inputs specified in list
run ui tests
Merge pull request #639 from optimizely/dfoxpowell/anim-placeholder-icons

Dfoxpowell/anim placeholder icons
Merge pull request #640 from optimizely/krush/pricing4

Krush/pricing4
Updated