Merge pull request #34 from planctechnologies/master

Authenticate with cloud provider (GNS-48)
Fixes #33. RAM and NVRAM IOU image settings not propagated when creating
the device.
Option to use default IOU RAM & NVRAM values. Avoid to silently not
display exceptions before the GUI has started.
Move cloud code to a builtin module and support for clouds on remote
servers.
Disconnect the server if the version differs with the GUI.
Remove .gns3 from folder name.
Bump to alpha4.
Hide the cloud page for alpha4 release.
Revert "Bump to alpha4."

This reverts commit 6adcaa6ddc78e22110227574efc9bf026ba815b3.
Revert "Hide the cloud page for alpha4 release."

This reverts commit f621266596b508c2dac11b04a2f0f92215d65af1.