add sleep and retry to azure setup script

[mwhooker]

• adds retry around azure cli comands
• adds configurable sleep between commands

lightly tested

closes #4007

[mwhooker]

turned off wifi during resource creation and the script looked like it restarted correctly:

info:    group create command OK
==> Creating storage account
info:    Executing command storage account create
+ Checking availability of the storage account name
+ Creating storage account
info:    storage account create command OK
==> Creating application
==> Creating service principal
==> Creating permissions
info:    Executing command role assignment create
+ Finding role with specified name
+ Creating role assignment
error:   Principal xxxx does not exist in the directory xxxx.
error:   Error information has been recorded to /Users/mwhooker/.azure/azure.err
error:   role assignment create command failed

Error creating permissions for: http://mattpacker4
createPermissions failed. Retrying...

Sleeping for 10 seconds to wait for resources to be
created. If you get an error about a resource not existing, you can
try increasing the amount of time we wait after creating resources
by setting PACKER_SLEEP_TIME to something higher than the default.

==> Creating permissions
info:    Executing command role assignment create
+ Finding role with specified name
-data:    RoleAssignmentId     : /subscriptions/xxxx/providers/Microsoft.Authorization/roleAssignments/xxxx
data:    RoleDefinitionName   : Owner
data:    RoleDefinitionId     : xxxx
data:    Scope                : /subscriptions/xxxx
data:    Display Name         : mattpacker4
data:    SignInName           : undefined
data:    ObjectId             : xxxx
data:    ObjectType           : ServicePrincipal
data:
+
info:    role assignment create command OK