Display deprecation warning for unused halt config properties

halt_timeout and halt_check_interval will be removed in the next version of Vagrant, 1.7.
Merge pull request #3599 from mitchellh/deprecate-warnings-for-unused-halt-config-props

Display deprecation warning for unused halt config properties
Update CHANGELOG
core: provider has default priority of 5
core: default provider chosen by usability and prority
Update tests
core: more intuitive logic around default providers
core: Can exclude providers
providers/docker: lower priority

We do this mostly because Docker is the only provider that using it
requires some amount of Docker-specific knowledge. VirtualBox, VMware,
etc. kind of "just work". It is not the likely case that someone does
a `vagrant up` and expects Docker, at this point.
core: Fix some tests, revert a change
core: dup the provider options so we can't overwrite them
core: fix final test
Merge pull request #3600 from mitchellh/f-default-provider

Default Provider By Priority
Update CHANGELOG
providers/docker: choose proper provider for host VM
Add colorization and log_level support to salt provisioner.

This commit adds two new options to the salt provisioner:

- `colorize`: controls color output. Defaults to no-color (present behavior).
- `log_level`: controls log level. Defaults to `debug` (present behavior).

Docs included!
Merge pull request #3603 from eykd/feature/colorize-salt-output

provisioner/salt: Add colorization and log_level support to salt provisioner.
website/docs: update slat docs
Update CHANGELOG
website/docs: Add missing `end` to "Run Once or Always" example