Custom voice speeds, duplication, fixes

We've shipped a bunch of smaller things we figured we'd keep to one update:

• We can now add custom speed settings to custom voices. For now, you'll have to ask us to make these changes in your account, but the ability is there if you need it.
• You can now duplicate templates, for when you want to play around without changing your live template.
• We've fixed automatic template generation to not time out.