Forbid controller and compute servers to be different versions.

Report last compute server error to clients and display in the server summary.

gns3server/version.py

@@ -23,7 +23,7 @@
 # or negative for a release candidate or beta (after the base version
 # number has been incremented)
 
-__version__ = "2.1.10dev1"
+__version__ = "2.1.10dev2"
 __version_info__ = (2, 1, 10, 99)
 
 # If it's a git checkout try to add the commit