Serve icons as images, not as fonts

[c-lliope]

using fonts requires developers to register them in their asset configuration file, as in:

https://github.com/thoughtbot/administrate/blob/gw-datetime/config/initializers/assets.rb

Additionally, we don't need an entire icon font when we're only using nine icons.

And lastly, it's still referencing bootstrap. Let's get rid of it.

[c-lliope]

This repository is no longer maintained. If you would like to take over the repo and gem, I can transfer ownership to you.

If so, please fork this repository, create a new issue called "Transfer Ownership", and @-mention me in the issue.

Thanks,
Grayson