Do not hardcode path to nohup (#1278)

Fix #1277.

Author: raxod502

watcher/straight_watch_nohup.py

@@ -13,4 +13,4 @@
 # using the Python in the virtualenv, we'll find that out right away,
 # since we are using the same execution path that will eventually be
 # used for the actual command run by nohup.
-os.execv("/bin/nohup", sys.argv)
+os.execvp("nohup", sys.argv)