Allow bind context for view handler

[evilpacket]

Allowing the view handler to accept a bind context makes it quite simple to pass in alternative context when you don't want params, etc.

Also this PR would not be possible without big <3's from @nlf

[nlf]

It was my suggestion here to intentionally ignore the request._route.env.bind context so that defaults set with something like plugin.bind don't apply, since there's a likelihood that's not what you want to pass to your view. So it's explicit bind on the route, or default behavior. Thoughts?

[hueniverse]

It's confusing using route bind as view context. Instead, I'm changing it to simply accept a handler with { view: { template: 'test', context: { message: 'hi' } } }.