feat scrollbar: Create getter & setter to watch scroll percentage

Improve LumX Scrollbar by adding getter and setter on the service. If the id of the scroll element is set, we can $watch the scrollPercent of a specific scrollbar using the getter.
feat scrollbar: Observe id to handle dynamics variables

Before, the id was set in plain text, we can now set a dynamic variable for it.
refactor scrollbar: fix jshint error
style scrollbar: Fit observe to Ollman Style
Merge pull request #62 from lumapps/feat/scrollbar

feat scrollbar: Create getter & setter to watch scroll percentage