Add prop types

[japamat0]

Issue [#41]

I added prop types and default props to the following components:

App.js
Burst.js
ErrorToast.js
Frame.js
Preview.js
Settings.js
Sidebar.js
SidebarButton.js
SidebarButtonWithBadge.js

Default props for connected components have been set to match initial state from the store, with there mapDispatchToProps functions have been set as simple arrow functions, i.e. () => {}. For non connected components, the default props have been set to match the properties applied where those components are rendered, i.e. where <Frame /> is rendered within <Preview />

@mmmaaatttttt & @alissarenz please review before @ctlusto

• thanks!