Remove flash + add example to show how flash works on packages

I just realized that we didn't need to use the implicit flash for most of the
views. So I removed them. I also created a tag for flash so that anyone can
easily inject the flash notification into their views by just adding
`@tags.flash()` in their views and adding the `implicit flash:
play.api.mvc.Flash`.

Note that I couldn't get flash working without the use of Redirects. Apparently
this is a known issue but no fix has been provided yet
[https://groups.google.com/forum/#!topic/play-framework/oGh3gTmzrLA]

To play with the flash stuff, just create a new Package. You should see the new
notification that says "Package Created!"