Fix truncation length calculation when comparing html input to max chars allowed

[seriouslysean]

This fixes an issue with the truncation length reported when using html input. This will fix the issue called out in https://github.com/kavalcante/vue-truncate-collapsed/issues/16.

Couple of things to note:

• Added prepare script to package.json to support installing the package from GitHub
• Converted <a> tags to <button>s for accessibility purposes
• Added a showToggle prop to completely hide the buttons when the input length does not exceed the max length

Let me know if you have any questions 👋