Move visible logic inside each button
Move click functionality inside each button
Extract getButtons function from Toolbox components to functions file

- add possibility to allow execution of the button's routine besides triggering
`toolbarButtonClicked` API event
- keep backwards compatibility
- get rid of `ToolbarButton`

* feat(toolbox) allow any toolbox button to be displayed as main

fixes the previous behaviour where only a certain set of buttons were whitelisted for being displayed in the main toolbar

* code review

* code review - fix avatar icon position

ESLint 4.8.0 discovers a lot of error related to formatting. While I
tried to fix as many of them as possible, a portion of them actually go
against our coding style. In such a case, I've disabled the indent rule
which effectively leaves it as it was before ESLint 4.8.0.

Additionally, remove jshint because it's becoming a nuisance with its
lack of understanding of ES2015+.

Prepare for React 16.

* feat(feedback): convert to react and redux

- For styles, remove "aui-dialog2" nesting so existing styles
  can be reused.
- Remove Feedback.js and replace with calls to redux for state
  storing and accessing.
- Add dispatching to FeedbackButton instead of relying on jquery
  clicking handling so the button can be hooked into redux.

* address feedback

* remove calling to not show feedback for recorder and filmstrip

When callstats is not configured hide the button.