Ansible: code cleanup and documentation update

Clean Up (code logic is kept unmodified):
* Remove repetition around `ansible.limit` option (merge conflict issue)
* Re-add missing comments from GH-1697 (merge conflict issue)
* Reorder instructions

Documentation for following changes:
* [GH-1697] add more options
* [GH-1979] extra verbosity option
Ansible: Support three available verbosity levels
Ansible Docs: Add beginner warning

Apply the same warning as in Chef or Puppet pages
Fixed options to NFS: no_subtree and check became no_subtree_check
[GH-1977] revert and alternate fix

@mitchellh, the internal encoding doesn't seem to work.  Therefore,
I reverted that previous change to vagrant.rb.

However, I found two alternate solutions.  Either transcoding,
`/etc/redhat-release` to ISO-8859-1 on open, or using something
like File.binread to transcode the file contents to raw.
Merge pull request #2158 from atomic-penguin/GH-1977

hosts/fedora: read as encoding
Merge pull request #2156 from gustavobgama/fix/master/linux_nfs_error

hosts/linux: fixed options to NFS: no_subtree and check became no_subtree_check
Merge pull request #2153 from gildegoma/ansible-docs-cleanup-and-vv

provisioners/ansible: Update documentation, Code Cleanup (and Extend Log Verbosity option)
Update CHANGELOG
hosts/arch: correct variable for NFS exports [GH-2161]