Remove workaround for early paramiko import

As discussed in the original bug [1] one of the reasons to not
daemonize after import of paramiko is that it creates a global
Crypto.Random() object which is used around the place, however the
close of fd's in the daemonize breaks that object's connection to
/dev/urandom.

However, it seems that this issue is no longer as paramiko now
directly uses urandom and has no global object [2].  Requirements is
updated to the first release after this change.

We have also removed the use of the global statsd object in
I6d339a8c631f8508a60e9ef890173780157adefd.

Thus we should be able to return this to it's simpler form

[1] https://github.com/paramiko/paramiko/issues/59
[2] 6f211115f4

Change-Id: I6cf3ba0df857f4213b0ec658ebd0511a24618175

nodepool/cmd/nodepoold.py

@@ -30,12 +30,9 @@ import signal
 import traceback
 import threading
 
-import nodepool.cmd
 import nodepool.builder
-
-# No nodepool imports here because they pull in paramiko which must not be
-# imported until after the daemonization.
-# https://github.com/paramiko/paramiko/issues/59
+import nodepool.cmd
+import nodepool.nodepool
 
 
 def stack_dump_handler(signum, frame):
@@ -112,7 +109,6 @@ class NodePoolDaemon(nodepool.cmd.NodepoolApp):
         os._exit(0)
 
     def main(self):
-        import nodepool.nodepool
         self.setup_logging()
         self.pool = nodepool.nodepool.NodePool(self.args.secure,
                                                self.args.config)

requirements.txt

@@ -3,7 +3,7 @@ pbr>=1.3
 gear
 PyYAML
 python-jenkins
-paramiko>1.9.0
+paramiko>1.11.6
 python-daemon>=2.0.4,<2.1.0
 extras
 statsd>=3.0