Unhardcode vif_pluggin and workers for Pike+

unhardcode the following options:
 * workers
 * vif_plugging_timeout
 * osapi_compute_workers

Change-Id: I4499ce4b73e4547e53a5d505c901378355897f2d
diff --git a/README.rst b/README.rst
index 8eaa2e2..90f2a4b 100644
--- a/README.rst
+++ b/README.rst
@@ -30,6 +30,8 @@
         workers: 8
         report_interval: 60
         dhcp_domain: novalocal
+        vif_plugging_timeout: 300
+        vif_plugging_is_fatal: false
         consoleauth:
           token_ttl: 600
         bind:
@@ -282,6 +284,8 @@
         resume_guests_state_on_host_boot: False
         preallocate_images: space  # Default is 'none'
         my_ip: 10.1.0.16
+        vif_plugging_timeout: 300
+        vif_plugging_is_fatal: false
         bind:
           vnc_address: 172.20.0.100
           vnc_port: 6080