Added support for working with the Salesforce test environment (i.e.
https://test.salesforce.com).
Added support for working with the Salesforce test environment (i.e.
https://test.salesforce.com).
Added support for Link Attachments to posts.
Added license to header of new files.
Merge pull request #5 from javamate/test-environment-support

Support for non-production environment & link attachments