fix(views): move 'Views' in archive filter sidepane

treat views as saved filters

SD-914
feat(stages): Introduce stages in Content and Tasks

+ Make stages part of 'desks' service
+ Create StagesCtrl for handling
+ Create sd-desk-stages directive to display stages within specific desk
+ Make 'Content' and 'Task' aware of stages

SD-903, SD-904
fix(stages): Code and style improvements

Add new styling for stages
Improve some parts of the code
fix(stages): Further code improvements
Merge pull request #494 from nidzix/stages-views

fix(views): Stages UI