Update htpasswd role to add "sequence of users" generation functionality

[tylerauerbeck]

In the create-users role in casl-ansible -- we have the ability to just provide a prefix and then generate a sequence of users based off of that prefix (i.e. provide lab-user and then generate lab-user1 - lab-user25). We should look to incorporate the same functionality in our new role in cases where we don't care about specific users.

[oybed]

Agreed ... and we should look to merge these 2 roles to avoid maintaining 2 roles.