Refactor pid selector into a directive

- move pid selector code into its own directive
- exposes $scope.activeProcess to the parent controller
- move pid selector CSS to menu.less
- move directive to Common ns
- Rename pid selector to use common namespace
- move rules to ./menus/pid-selector.less
Merge pull request #495 from strongloop/feature/profiler-navbar

Refactor pid selector into a directive

- move pid selector code into its own directive
- exposes $scope.activeProcess to the parent controller
- move pid selector CSS to menu.less
- move directive to Common ns
- Rename pid selector to use common namespace
- move rules to ./menus/pid-selector.less

Fix #490