Here's a quick run through of how to get this running on a dev version of Bolt. It should hopefully be fairly simple.
#####If you use composer to pull / update bolt then this method will work
First add this repo to your composer.json so that it loads from github rather than Packagist.
....
"repositories": [
{ "type": "vcs","url": "https://github.com/bolt/bolt-thumbs"}
],
....
Then add bolt/thumbs as a requirement for the project.
"require": {
.....
"bolt/thumbs": "dev-master",
.....
}
running a composer update should now get you the package. Then all we need to do is mount it as a controller.
To do this, just make one modification to the main Bolt\Application file in side the initMountpoints() methods and add in this mount command:
// Mount the 'thumbnail' provider on /thumbs.
$this->mount('/thumbs', new \Bolt\Thumbs\ThumbnailProvider());
#####If you manually manage your install without Composer:
Download this project and put it somewhere in your project.
If you are not using composer all you need to di is make sure is that the bolt-thumbs package can autoload correctly.
Add the same line as above to your Bolt\Application initMountpoints() method. Then download this package and make sure that the classes can be autoloaded.