Reverse the order of nested templates. (#531)

Reverse the order of nested templates. (#531)

Reverses the order of nested template declaration.

This way templates that depend nested templates over the same
hook are ensured to run in the proper order.

Ensures consistency of run-order template includes, for both
base yml files, and nested template yml

eg:

base.yml
```
templates:
  - "templates/template1.yml"
hooks:
  after_code:
    - exec: cat "/tmp/file_made_from_template1.yml.txt"
```

template1.yml
```
templates:
  - "templates/template2.yml"
hooks:
  after_code:
    - exec: cat "/tmp/file_made_from_template2.yml.txt"
    - exec: echo "data from template1" > /tmp/file_made_from_template1.yml.txt
```

template2.yml
```
hooks:
  after_code:
    - exec: echo "data from template2" > /tmp/file_made_from_template2.yml.txt
```