Vagrantfile can't find vagrant-omnibus correctly

The string for detecting the Omnibus plugin has changed: `Omnibus` ->
`vagrant-omnibus`.

Obvious fix.
Merge pull request #38 from docwhat/patch-1

Vagrantfile can't find vagrant-omnibus correctly
[COOK-4125] - chef-server is not reconfigured after updating

Signed-off-by: Sean OMeara <someara@opscode.com>
[COOK-4176] - Ensure creation of `:file_cache_path`

Signed-off-by: Sean OMeara <someara@opscode.com>
[COOK-4178] - update Bento boxes used in chef-server cookbook

Signed-off-by: Sean OMeara <someara@opscode.com>
Updating test-harness, fixing up style cops, adding amazon linux support to Omnitruck library
Version bump to 2.1.0
Publish 2.1.0 Changelog
Version bump to 2.1.1 (for development)
[COOK-4386] - package_options attribute added

Signed-off-by: Sean OMeara <someara@opscode.com>
Version bump to 2.1.2
Publish 2.1.2 Changelog
Version bump to 2.1.3 (for development)
dropping git dep
Version bump to 2.1.4
Publish 2.1.4 Changelog
Version bump to 2.1.5 (for development)