Unable to add a primitive in a group in a given order using pcs

Issue

• pcs should enable to add a primitive in a group at a given order. For example, if there is a group already configured:

  Resource Group: GROUP1
       Primitive1
       Primitive3
  

  pcs should allow me to add a Primitive2 after primitive1, either with an option --order , or an option --after
  so that we could execute a single pcs command such as:

  pcs resource create Primitive2 ........ --group GROUP1 --after Primitive1
  

  and therefore get the group:

  Resource Group: GROUP1
       Primitive1
       Primitive2
       Primitive3