Rename component files using PascalCase

[ollelauribostrom]

We should probably rename the component files using PascalCase to reflect the component names.

• app.js -> App.js
• change-button.js-> ChangeButton.js
• char.js -> Char.js
• github-corner.js -> GithubCorner.js
• hint.js -> Hint.js
• logo.js -> Logo.js
• progress-bar.js-> ProgressBar.js
• rebus.js-> Rebus.js
• word.js -> Word.js

[mbomfim33]

On it

[mbomfim33]

@ollelauribostrom, @vanwykjd,

Just made the PR. Let me know if there is any other changes required.