[Issue#115] : add onboarding page when extension is first installed

[ask-imran]

This PR is part of issue#115

Changes made:

• add a new onboarding page when the extension is installed the first time
• refactor the code to add bootsrap.js to have common functionalities which can used by both popup and onboarding

Things to further improve (This could be on a separate PR) :

• add values in other locales for newly added string
• The popup & onboarding have JS duplicated, this could be overcome by adding a bootstrap for popup and utilizing the bootstrap.js
• The common CSS could be extracted into its own file
• add git changelogs
• remove Enable Survol on this page from onboarding page ✅

[mdolr]

Thank you for your PR

I've changed some things, trying to make the onboarding page look like the popup. Also I removed the "enable on survol on this page" parameter as it doesn't make any sense here.

I'm unsure about the gif idea honestly. I think we should use something else. Also maybe we could add a way to show the changelog using the Git releases feed ?

[ask-imran]

I'm unsure about the gif idea honestly. I think we should use something else. Also maybe we could add a way to show the changelog using the Git releases feed ?

Let me know if you have other thoughts around, I can remove the gif. I kind of looks gigantic now. I'll look at the git releases feed

[ask-imran]

Hey @mdolr,
I had some look around the git release, I feel we could use github api for the latest release instead of the feeds.

Let me know your thoughts

[ask-imran]

Added github release note, exclude prerelease check, display last release

[mdolr]

Great changes, I'm waiting for #131 which adds a new setting and then I'll be able to merge this