Update images.js

Hi, there is a bug in Openstack where you cannot set the metadata of os_type as it is overwritten to None when first creating the image. This causes a problem with the timezone not being set correctly on windows machines. To solve this, I wrote a function, updateImageMeta, that allows a client to update the metadata of an image , after calling createImage function, and wanted to share it so maybe it will be in future versions of pkgcloud and help other people who might need this functionality as well.
Create meta-test.js
Create metaResponse.json
Update meta-test.js
Update images.js
Merge branch 'master' into pr/251
Cleaning up artifacts from merging an old PR
Cleaning up meta-test code after PR