Handle startup-config push using base64

Dynamips working directory management
Random port selection for the ZeroMQ server
TCP & UDP port allocation in a range with improvements
Update Dynamips to 0.2.11 (for the tests)
Focus on Python3 development (stop trying to be compatible with Python
2.x)
More error/bug catching

tests/dynamips/test_hypervisor.py

@@ -18,9 +18,9 @@ def test_host(hypervisor):
     assert hypervisor.host == "127.0.0.1"
 
 
-def test_workingdir(hypervisor):
+def test_working_dir(hypervisor):
 
-    assert hypervisor.workingdir == "/tmp"
+    assert hypervisor.working_dir == "/tmp"
 
 
 def test_path(hypervisor):