Update to azure-sdk-for-ruby 0.6.4

## Update to Latest Version of azure-sdk-for-ruby

- update the gem spec to the 0.6.4
- change the way add_role in handled due to breaking change in azure-sdk-for-ruby create_virtual_machine method. The add_role method is called after create_virtual_machine conditionally
- add in gitignore for .idea/ to help with anyone using rubymine

Perhaps, these changes will fix the following:
- https://github.com/MSOpenTech/vagrant-azure/issues/37