playbook: Extract SlapOS master URLs to separate setting

It is required in order to being able to use vars_prompt in slapos
playbook, while keeping compatiblity with other playbooks.

playbook/imt-server.yml

@@ -4,6 +4,7 @@
 
   vars_files:
     - settings/imt.yml
+    - settings/slapos-master.yml
 
   vars_prompt:
     - name: "computer_name"

playbook/settings/slapos-master.yml

+---
+slapos_master_url: https://slap.vifib.com/
+slapos_web_master_url: https://slapos.vifib.com/
\ No newline at end of file

playbook/settings/vifib.yml

 ---
 re6st_registry_url: http://re6stnet.nexedi.com/
 re6st_fingerprint: sha256:61a8f3ef4bdf12aca0dad5c17e8fadd15966bdd68b1400c91ef8ee53f17c0d65
-slapos_master_url: https://slap.vifib.com/
-slapos_web_master_url: https://slapos.vifib.com/
 interface_name: lo
 re6st_annon: True
 re6sttoken: noname

playbook/slapos-test-node.yml

@@ -4,6 +4,7 @@
 
   vars_files:
     - settings/vifib.yml
+    - settings/slapos-master.yml
 
   vars:
     interface_name: eth0

playbook/vifib-shuttle.yml

@@ -8,6 +8,7 @@
   vars_files:
     - settings/vifib.yml
     - settings/upgrader.yml
+    - settings/slapos-master.yml
 
   vars_prompt:
     - name: "computer_name"

playbook/vifib.yml

@@ -8,6 +8,7 @@
   vars_files:
     - settings/vifib.yml
     - settings/upgrader.yml
+    - settings/slapos-master.yml
 
   vars_prompt:
     - name: "computer_name"