Add Digital Ocean support.
Libcloud update

  also fix args for rackspace driver
fix logic error for ec2 machines of state Unknown
add name validation for Linode add machine
Automated build of mist.js
Properly handle backend add.

* validate backend before adding,
* warn with proper msg if failed backend already added
Fix add_backend user handling.

We need to make sure that the user dict is updated before validating.
The same stands for removing the backend after checking that libcloud
cannot connect.
Properly handle backend add.

- validate backend before adding,
- warn with proper msg if failed backend already added

We need to make sure that the user dict is updated before validating.
The same stands for removing the backend after checking that libcloud
cannot connect.
Automated build of mist.js
fix backend button positioning
Merge branch 'staging'
Merge branch 'master' into single_view_link