Simplify domain language to just "boot" and unscoped config keys

lib/mrsk/cli/app.rb

@@ -13,7 +13,7 @@ class Mrsk::Cli::App < Mrsk::Cli::Base
           execute *MRSK.app.tag_current_as_latest
         end
 
-        on(MRSK.hosts, **MRSK.group_strategy) do |host|
+        on(MRSK.hosts, **MRSK.boot_strategy) do |host|
           roles = MRSK.roles_on(host)
 
           roles.each do |role|

lib/mrsk/commander.rb

@@ -51,9 +51,9 @@ class Mrsk::Commander
     end
   end
 
-  def group_strategy
-    if config.boot.group_limit.present?
-      { in: :groups, limit: config.boot.group_limit, wait: config.boot.group_wait }
+  def boot_strategy
+    if config.boot.limit.present?
+      { in: :groups, limit: config.boot.limit, wait: config.boot.wait }
     else
       {}
     end

lib/mrsk/configuration/boot.rb

@@ -4,8 +4,9 @@ class Mrsk::Configuration::Boot
     @host_count = config.all_hosts.count
   end
 
-  def group_limit
-    limit = @options["group_limit"]
+  def limit
+    limit = @options["limit"]
+
     if limit.to_s.end_with?("%")
       @host_count * limit.to_i / 100
     else
@@ -13,7 +14,7 @@ class Mrsk::Configuration::Boot
     end
   end
 
-  def group_wait
-    @options["group_wait"]
+  def wait
+    @options["wait"]
   end
 end