typo
Update README.doc to fix spelling error
Ignore users if we've already seen them

For environments with duplicate users in different password databases,
such as files and ldap, ohai was using the _last_ entry returned by
`getpwent` but the system uses the first.

Incorporate feedback from @sersut
ec2_metadata: specify path in exception

The current message is rather unhelpful to establish what exactly fails,
eg:

    DEBUG: Plugin Ec2 threw #<RuntimeError: Encountered error retrieving EC2 metadata (returned 404 response)>
    DEBUG: /opt/chef/embedded/lib/ruby/gems/1.9.1/gems/ohai-7.0.2/lib/ohai/mixin/ec2_metadata.rb:104:in `metadata_get'
    DEBUG: /opt/chef/embedded/lib/ruby/gems/1.9.1/gems/ohai-7.0.2/lib/ohai/mixin/ec2_metadata.rb:120:in `block in fetch_metadata'
    DEBUG: /opt/chef/embedded/lib/ruby/gems/1.9.1/gems/ohai-7.0.2/lib/ohai/mixin/ec2_metadata.rb:113:in `each'
    DEBUG: /opt/chef/embedded/lib/ruby/gems/1.9.1/gems/ohai-7.0.2/lib/ohai/mixin/ec2_metadata.rb:113:in `fetch_metadata'
    DEBUG: /opt/chef/embedded/lib/ruby/gems/1.9.1/gems/ohai-7.0.2/lib/ohai/mixin/ec2_metadata.rb:130:in `block in fetch_metadata'
    DEBUG: /opt/chef/embedded/lib/ruby/gems/1.9.1/gems/ohai-7.0.2/lib/ohai/mixin/ec2_metadata.rb:113:in `each'
    DEBUG: /opt/chef/embedded/lib/ruby/gems/1.9.1/gems/ohai-7.0.2/lib/ohai/mixin/ec2_metadata.rb:113:in `fetch_metadata'
    DEBUG: /opt/chef/embedded/lib/ruby/gems/1.9.1/gems/ohai-7.0.2/lib/ohai/plugins/ec2.rb:52:in `block (2 levels) in <main>'
OHAI-566: Update changelogs
Merge pull request #63 from Erkan-Yilmaz/master

Meets "Obvious fix" requirements
Merge pull request #88 from dkullmann/patch-1

Update README.doc to fix spelling error

Obvious fix.
Convert README to md and update dev instructions

* Purge wiki references, links to new docs site instead
* Update dev instructions for bundler.
de-opscode-ify README
Link to Ohai's contributing guidelines
ninja fix busted README.rdoc reference
recreate OHAI-182 branch
OHAI-182: release notes
Contribution info for OHAI-561.
Merge pull request #303 from swalberg/getpwent_duplicates

[#OHAI-561] Ignore users if we've already seen them
Merge pull request #334 from opscode/sersut/CC-99

Contribution info for OHAI-561.
Remove ruby-wmi dependency
Add missing requires that are needed outside of tests and normal binary execution
Move Windows-only deps to Windows section
WMI utility refactoring