Change badge for development build tests.

The `development` branch should use it's appropriate branch badge.
Documentation update.

Added step to run installation command and register service provider.
Rename default configuration file.

Changed from `lazystrings.php` to `config.php` to be able to access the package config correctly.
Access config file as `lazy-strings`

This way we can access the config file in `app/config/packages/nobox/lazy-strings/config.php` the same way as if it was generated by the command line in `app/config/lazy-strings.php`

Also the generator uses the correct file name.
Change name of default folder for storage

Now it's `lazy-strings`
Update tests and stubs to reflect new changes.

Changes on config file names and default storage folder.