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
website/docs: Fix link to global-status command
fix chef version checking

the version checking here uses a function which is intended only
for chef cookbook versions, which must be x.y or x.y.z.  when fed
a legal chef prerelease version the prior code throws an exception:

[2014-05-01T22:08:01+00:00] FATAL: Configuration error Chef::Exceptions::InvalidCookbookVersion: '11.14.0.alpha.1' does not match 'x.y.z' or 'x.y'
[2014-05-01T22:08:01+00:00] FATAL:   /tmp/vagrant-chef-2/solo.rb:6:in `from_string'
[2014-05-01T22:08:01+00:00] FATAL: Aborting due to error in '/tmp/vagrant-chef-2/solo.rb'

since we only need to compare the major and minor version numbers a
simple #to_f sufficies for this test.

alternative, we could use Gem::Version here, but i didn't really see
the need to...
remove require
Merge pull request #3604 from lamont-granquist/lcg/fix-prerelease-versions

fix chef version checking