Added user option to configure 'cache_prefix'.
Added test cases and updated existing ones so they'll provide Config service to mocked objects.
Added config example and updated packagist link to point to slm/cache instead of slm/mail
Added user option to configure 'cache_prefix'.
Added test cases and updated existing ones so they'll provide Config service to mocked objects.
Added config example and updated packagist link to point to slm/cache instead of slm/mail
fix indentation
Merge pull request #4 from marcelo-lipienski/master

Added configurable cache_prefix