JPEG mime registration generates warning when used as a gem

[pixeltrix]

When using fleximage as a gem a warning is generated by the registration of the image/jpeg mime type and its alias image/pjpeg. I think this warning is also generated when installed as a plugin but its swallowed during the initial plugin loading. Also looking at the code for register_alias it's the wrong method - it should be registered as a mime type synonym. My fault since I added it in the first place.

Anyway a fix for this can be found in this commit.

[jlsync]

yes, this is annoying me no end. thanks for fixing.

[robinboening]

thanks!