Disable the NumericLiterals cop for rubocop

- Disable the NumericLiterals cop in the .rubocop.yml file - this cop enforces
  an underscore '_' every 3 characters of an integer. This doesn't make much
  sense in our use case and reduces readability. Especially for port numbers.
- Remove any existing entries that were abiding by the NumericLiterals
  cop.

Change-Id: I8ddd828f372050cac38b8c384ed4952b98836313
Addresses: blueprint rubocop-integer

.rubocop.yml

@@ -14,6 +14,9 @@ Encoding:
     - metadata.rb
     - Gemfile
 
+NumericLiterals:
+  Enabled: false
+
 LineLength:
   Enabled: false
 

attributes/default.rb

@@ -80,7 +80,7 @@ default['openstack']['image']['api']['cache']['image_cache_max_size'] = '1073741
 default['openstack']['image']['cache']['dir'] = '/var/lib/glance/image-cache/'
 # Number of seconds until an incomplete image is considered stalled an
 # eligible for reaping
-default['openstack']['image']['cache']['stall_time'] = 86_400
+default['openstack']['image']['cache']['stall_time'] = 86400
 # Number of seconds to leave invalid images around before they are eligible to be reaped
 default['openstack']['image']['cache']['grace_period'] = 3600