Rsync default behaviour

[stepanzarubin]

I think default behaviour should be:

When we run rsync it should do full rsync
When we run rsync-auto it should first do full rsync and then watch for modified only.

This should affect all the plugins that are using Vagrant rsync internals.

Thanks.

[nuncanada]

For big directory structures that are common for a lot of projects, even more for development workbenchs, this is the difference between a usable vs non-usable rsync solution.

[sethvargo]

Oops - looks like a duplicate of #6399 actually. Thanks!